GamuT M250i Mono Power Amplifiers

It’s my turn to get in on all the GamuT fun. Our publisher has been using GamuT speakers for years now and managing editor Rob Johnson is smitten with the D3i preamplifier.

Of the few manufacturers that build a full complement of electronics and speakers, they voice things differently. Burmester, for example, produces speakers that are somewhat forward, punchy and a little tipped up on the bottom and the top, yet the electronics are very warm sounding, almost tube-like, though fully solid-state.

GamuT however, is somewhat different. The speakers have an incredibly natural voice, and the electronics even more so. Even though their electronics and speakers produce perfect synergy, as you might expect because their components are much more neutral, tonally speaking, you do not have to have an all-GamuT system to achieve great results. Though you just might want to for simplicity’s sake.

Like the average Dane, the M250i is slim. 84 pounds (38kg) is substantial, but not what you’d expect a 250-watt per channel (into an 8 ohm load) that doubles into 4 ohms and still produces 900 watts into 2 ohms. Lifting the cover with the GamuT logo, it’s easy to see why; the power supply is huge! Unlike some solid-state amplifiers that require a huge bank of output devices to produce high power, GamuT uses two really big MOSFET transistors per channel, capable of passing 400 peak amperes of current each. Naim also takes this approach with their 500 series amplifier and the result is very special. Two transistors means no device matching is necessary, with none of the associated problems. Less is more.

While on that subject, the M250i has an interesting bit of simplicity or complexity, depending on how you look at it. On the rear panel, there are two sets of speaker outputs that you might mistake to use to bi-wire a pair of speakers. Don’t do it. One has a traditional resistor and coil output filter, as many solid state amplifiers do, more suited to ESL speakers and those with more difficult impedance loads, while the other outputs (the ones closer to the heatsinks) are direct coupled outputs. GamuT claims that either way, you can’t hurt these amplifiers, but I did follow their lead when using my pair of Quad 63s.

Inputs are via RCA or balanced XLR, and this is a fully balanced amplifier, so that mode will provide the best results. It’s worth mentioning that it is tough to tell the difference in sound using the ARC REF5 preamplifier, which sounds equally good through it’s balanced, and RCA outputs––and I have equally impressive results with my CJ Act Two preamplifier, which is RCA only.

Danes are usually somewhat reserved, but the GamuT manual is not only well written but also pretty amusing to read. They make great points about setup, cables and gain, mentioning that “at 4 ohms, full output power is more than 151,000,000,000,000,000 times larger than the input noise power.” A cursory listen confirms that these monoblocks are indeed quiet.

Not only does this provide a fatigue-free sound, but I’m sure this simple design contributes to another wonderful aspect of the M250i: it sounds incredible at low volume. Amplifier genius and mad scientist Nelson Pass likes to say that if the first watt isn’t great, the rest don’t matter. The M250i exemplifies this philosophy. Make no mistake, when you want to crank AC/DC or Skrillex, the M250i is fully capable. The cannon shots at the end of “For Those About to Rock” are awesome and have the necessary “crack” upon ignition without blur.

Mated to my Vandersteen 5A speakers, which are just slightly warm tonally, the M250i proves a perfect match for the rest of my system, utilizing an Audio Research REF 5 preamplifier. For decades I’ve been a fan of a great tube preamplifier mated to a powerful solid-state power amplifier to reap the rewards of both. The M250i does not disappoint in any way.

Never edgy or strident, the M250i’s feel a little foggy when powered up from ice cold. They only draw 50 watts in standby mode, so unless your energy habits have you immersed in guilt, I say leave them plugged in all the time. Otherwise, expect about 30 minutes before they reach full capability.

Unless you have the world’s most inefficient speakers, your ears will run out of headroom before the M250is will. Even listening at brain damage levels, these amplifiers do not run overly hot, so you will not be able to heat your listening room with them. Even after exhausting my record collection, I find it impossible to overdrive or overheat the GamuT amplifiers. I am most impressed at how they fail to draw any attention to themselves – they merely let the music flow.

What I do notice is the way these amplifiers render the finest of detail without ever sounding harsh, strident, or particularly solid-state in character. Well-worn recordings feel brand new again. A TONE favorite, the Crash Test Dummies’ Give Yourself a Hand, is full of sonic surprises. With extra overdubs and little vocal anomalies floating all around my listening area, it is almost like consuming something illegal. The only thing I didn’t really get to explore was the depth of the M250i’s bass response, as my Vandersteens only need the main power amplifier to go down to 80hz. But our publisher put them to the full test.

Spending way too much time with the entire Neu! catalog offers up the same results with jangly guitars and driving rythym in full force. Not happy to stop there, a couple of evening’s worth of Eno’s Ambient series, finishing up with the classic Ambient 1: Music For Airports is marvelous. Eno’s gentle touch on the keyboard is even more delicate than I remember, with decay that seems to go on forever. Even this vacuum tube lover finds plenty to love here, and it really has me considering a pair for myself, especially in light of just having bought 16 KT120 tubes!

The GamuT amplifiers are a statement product, and for all but the most insane audiophile, should easily be the last power amplifiers you’ll need to buy. They offer musical delight with no negatives whatsoever. Enthusiastically recommended.

Additional listening – Going all GamuT

After discussing the performance of the GamuT M250i amplifiers with Rob and Jerold, we all agree that they stand on their own as world-class power amplifiers. In the context of tube and solid-state systems, they integrate easily into whatever components you happen to be using. Thanks to their high current capability, they drive any speaker with ease. Though class AB in design, their lack of grain reminds me of a class-A amplifier, or the Burmester 911.

The M250is join a very elite group of solid-state amplifiers that just reveal music, not really sounding like transistor amplifiers or vacuum tubes. As one of the few manufacturers that can successfully build electronics and speakers with equal prowess, a complete GamuT system is wonderful. And for someone wanting an incredibly high performance audio system without the anxiety of trying to choose the right amp, preamp, speakers and digital player, I suggest an all-GamuT system. Complete the system with a set of their power cords, interconnects and speaker cables – one stop shopping!

Mated with their preamplifier and the recently reviewed RS5 speakers provides a highly compelling and dynamic system that can play anything you can throw at it with ease. Mixing it up with different amplification proves more different than better or worse. The Audio Research GSPre and GS150 offer up a bit more holographic, three dimensional presentation, while the mighty Pass Xs Pre and Xs300 monoblocks present a slightly warmer tonal balance and a little more slam. Keep in mind that these are hairsplitting differences; you won’t go wrong either way.

Of course the M250is sound lovely with my reference GamuT RS5 and S9 speakers. I’ve heard the M250is at a number of trade shows, and the match with GamuT speakers is as close to perfection as it gets. Just as these monoblocks work well in tandem with other preamplifiers and source components, they should be able to drive anything. Torturing them with Quad, MartinLogan and Acoustat ESLs is a breeze, and they work equally well with the Epicon 8s from Dali we recently had in for review as well as the Dynaudio Evidence Platinum speakers. I even lugged them to a friend’s house with a pair of old Apogee Divas! Nothing presents a problem to these high current powerhouses.

Because Mr. O’Brien’s Vandersteen 5A’s are passively crossed over at 80Hz, I spent quite a bit of time examining the bass character of the M250is. Whether I was enjoying “Dark Side of the Moon” or “Bitch Better Have My Money,” these amplifiers provide weight, control and fine detail. A perfect balance is struck in texture, never under nor overdamped, something that is easy to notice with speakers like the GamuTs, which reproduce ultra low bass with ease, and often a hallmark of massive solid-state amplifiers.

Great as the M250is are with GamuT speakers, they are particularly good with the current Quad 2815s too. These speakers are mercilessly revealing and finicky to get good sound from, yet the GamuT amplifiers deliver a presentation that is smooth and dynamic, along with being controlled and forceful in the lower register––something not easy to achieve with the Quads. The thundering bass line in Bowie’s classic “Fashion” was wonderful to experience, yet in the middle of the dissonant piano solo in “Aladdin Sane,” the bass line is well articulated, holding its own space brilliantly between the keyboard and Bowie’s vocal. These are indeed special amplifiers, no matter what speakers you own and whatever your musical choices might be.

-Jeff Dorgay

The GamuT M250i Monoblock Amplifiers



Analog Source             SME20 turntable/SMEV Tonearm, Sumiko Palo Santos cartridge

Digital Source Simaudio MOON 750D

Phonostage                  Audio Research REF Phono 2

Preamplifier                Audio Research REF 5

Cable                           Nordost Frey

Speakers                      Vandersteen 5A

AURALiC Merak Monoblock Amplifiers

China’s AURALiC, a relative newcomer to the hi-fi industry, has stepped into this crowded scene with some quality products, and the company sets a high bar for itself with each new release. Seeing AURALiC’s new MERAK monoblocks (priced at $5,000 per pair) freshly out of their packaging is a bit like seeing a great tuxedo-wearing magician backstage before a much-anticipated performance. It’s easy to admire the polished outward appearance, but as anticipation begin to grow, it becomes clear that something interesting will happen when the curtain rises, leaving one to wonder if the performance will live up to expectations.

Smoke and Mirrors?

In every way, these amps offer substantial build quality and beautiful fit and finish. The sleek, brushed metal exteriors of my test pair sport a matte-silver finish—but the modest exterior does not reveal what’s hidden beneath the handkerchief. These mono monsters offer 400 watts of juice into 4 ohms and half of that into 8 ohms. According to AURALiC, the MERAKS’ capacitors hold enough energy to deliver 16 amps of peak current and 900 watts of power. By comparison, my reference amp—a Mark Levinson 335 stereo amp—pushes 500 watts into 4 ohms. From a power perspective, I never feel that my power-hungry Piega P10 speakers are limited with the Meraks in the chain.

Not a full Class D design, AURALiC refers to the MERAK as a hybrid design using Class-A signal amplification, switching output stage and linear power supply, sounding surprisingly like another very exciting amplifier that graced our cover a couple of years ago. In daily use, these monos never get hot, even when they are powered up for a couple weeks continuously. In addition to the stellar energy efficiency of the MERAKs, their design allows the user to stack them in an audio shelf without worry of overheating. Each amp measures 11 inches wide, 11 inches deep, and 2.75 inches high, so even in a two-tier configuration the amps’ physical footprint remains modest.

By sharp contrast, moving my Mark Levinson 335 stereo amp (which should have come with a coupon for a hernia operation) requires a friend, or a couple post-move aspirin. The MERAKs, which weigh 18.7 pound apiece, are extremely easy to carry by comparison. In fact, I’m able to carry one amp under each arm and still have a spring in my step.

Sleight of Hand

Connecting the amps is as simple as expected. I must give AURALiC kudos for including Cardas CE binding posts with the amps. Clamping a single knob down onto a tough plastic bracket holds my speaker cable’s spade terminations against the posts. And it’s so easy to get a good finger hold on the knob that I don’t need a post wrench (or a kung-fu grip) to get a tight cable connection. I should note that this knob-bracket combo does not accommodate banana cable terminations.

The MERAK s offer only balanced XLR inputs, and so given my single-ended preamp, I choose to enlist the help of some adapters. After contacting AURALiC to see if they have any specific recommendations for or against that approach, I get the thumbs-up for adapters, which do the trick. After testing them with my Levinson to ensue they don’t color or cloud the sound to any significant degree, the adaptors are easy enough to drop in place. Once flicking the rear switch to activate the amp, pressing a small button on the front puts them in and out of standby mode, which a small LED indicates.

Firing up the MERAKs without source material playing, I’m amazed by their silence. If it weren’t for the LED indicator, I’d wonder if they were powered up at all. With the rest of my audio chain shut down, only the ribbon tweeter of my Piegas can reveal any audible hiss—and only when I put my ear against it. I leave the amps on for two weeks straight for both burn-in and stress testing and I never experience anything from my listening position except great music. That’s a disappearing act indeed!

Rabbit from a Hat

Switching designs inherently bring a lot of positive merits. First, their power-to-weight ratio offers very good value for the dollar. They also sip energy (rather than gulping it), which makes them the more environmentally friendly option. These amplifiers have come a long way in the last few years, but I generally find them lacking some of the subtle detail, frequency extension, and sonic emotion I’m accustomed to with class-A or AB designs. But contrary to my assumed impressions, the MERAKs provide some very welcome surprises that challenge my past views in meaningful ways.

During my first listening session, covering about 20 tracks of various music types, several characteristics stand out immediately. The MERAKs do not romanticize the sound, nor do they leave it overly stark and cold. They strike the right balance. They also do a very nice job of creating the ambience and reverberation around the musicians.

Also impressive is the soundstage they throw, which is both wide and tall. There are no perceived boundaries and the sound extends well beyond the speakers. Additionally, they do a very good job of layering instruments in depth. Music reveals itself both in front of and behind the plane of the speakers. Vocals stand out front and the other instruments fall into their proper alignment behind the vocalist. This characteristic is one of the MERAKs strengths and it’s very engaging with all types of music. Few tracks illustrate this better than Portishead’s Roseland NYC Live on vinyl. When delivering the track “Roads,” the MERAKs pull Beth Gibbons’ voice out front such that the illusion of the singer extends into the room and creates an appropriately upfront but unaggressive presentation. There’s no stridency, and vocals retain the engagement they should command. The MERAKs also place the sound of the crowd clapping along well into the background.

Enya’s album Watermark does present two noticeable downsides that my Levinson does not. First, with all the juice that the MERAKs bring, they most definitely take control of the speakers and maintain a tight command, which results in the bass losing a bit of low-frequency punch and definition and the highs losing a bit of sparkle. Secondly (and more subjectively), there’s a reduction in the underlying emotion of the song.

It’s hard to put a finger on this at first, but after listening to several tracks on various albums—both digital and vinyl—I notice a consistent signature to the MERAKs. There’s a slight veil, which results in the reduction of the nuanced detail and delicacy that gives increased realism to good recordings. Of course, this quibble is in comparison to an amplifier priced around $8,000, yet the Meraks run for only $5,000 a pair. At that price difference, I’d expect the Levinson’s performance to exceed the MERAKs’ by a significant margin.


Delivering the disco-y tunes Daft Punk’s Random Access Memories, proves to be a joy, with a very nice integration of instrumentation, and the perceived pacing of the music brings a captivating energy to the recording. A remastered Royal Edition recording of Mozart’s symphony No. 36 performed by Leonard Bernstein and the New York Philharmonic also illustrates the MERAKs’ prowess with wide dynamic swings.

Pink Martini’s “Omide Zendegani,” and other tracks from Get Happy, similarly reveals an ability to pristinely render more intimate songs with a small combination of vocals and instruments. But, where necessary, the amps are also able to decipher a complex array of instruments across the soundstage.

Take a Bow

As with a great magician, it’s hard not to be impressed with MERAKs’ capabilities and finesse. Of the class-D designs I have experienced so far, these top my list sonically – I’m sure the hybrid design contributes to this sense of ease in a big way. Compared to my favorite class-A and class-AB amps, the MERAKs have only a few tradeoffs, as noted above. At the same time, there is a lot to love—and kudos again to AURALiC for taking switching amplifier design further toward an elusive sonic pinnacle than my past experiences. Even when mated with very revealing and power-hungry speakers, the MERAKs never take the sound into the realm of stridency, and considering their other merits, it’s easy to settle in for a long listening session of great music.

While $5,000 is a significant financial commitment for most people, what you get with these amps represents great value in terms of watt-per-dollar ratio. There are many good amps in this price range, so the MERAKs face some stiff competition—but with oodles of power and very good sonics, these amps are certainly worth your consideration.

Additional Listening

The folks at AURALiC are on a roll.  We’ve had the pleasure of listening to almost their full line now, and they all share an equal level of sonic excellence, build quality and elegant visual understatement.  Best of all, the gear is reasonably priced, over delivering for the prices asked.  This just might be the next big brand in world of hifi, no small achievement.

I concur with Rob on all of his observations, and feel that the MERAKs strike a fantastic balance of timbral and tonal accuracy, major dynamic slam and a complete lack of fatigue.  Putting them through their paces with the KEF Blades, the Focal Maestro Utopias and the Dynaudio Evidence Platinum speakers proved the $5,000 pair of AURALiC amplifiers were not out of place in a six figure system.

However, like every other switching amplifier I’ve had in the listening room, the MERAKs benefit from careful attention to what’s coming from the AC line.  While they offer great sonics just plugged into the wall, a top notch power line conditioner will take them to an even further level of clarity.  And, should you need a bit of warmth in the mix, you can always pair these amplifiers with your favorite vacuum tube preamplifier.

In short, the AURALiC MERAK amplifiers offer tremendous sound for a very reasonable price.  We look forward to see what they will come up with next.  Maybe a 250 watt per channel stereo amplifier in one box?  Hmmm.

MERAK monoblock amplifiers

MSRP: $5,000 per pair


Speakers Piega P10
Amplifier Mark Levinson No. 335
Preamplifier Coffman Labs G1-A
Digital Sources Audio Research CD3 MKII    Light Harmonic DaVinci DAC    HP 2.5 GHz Quad Core running Windows 7 and JRiver Media Center 19.0.32
Analog Source Marantz TT-15 turntable with Clearaudio Virtuoso cartridge
Cables Jena Labs Valkyrie and Symphony interconnects    Jena Labs Twin 15 speaker cables
Power Running Springs Audio Haley power conditioner    Cardas Golden and Golden Reference/Mongoose power cords
Accessories Mapleshade SAMSON racks and shelves    ASC TubeTraps    Cathedral Sound room-dampening panels    Coffman Labs equipment footers

Boulder 3050 Monoblock Amplifiers

What do you get for a whopping $205,000 dollars?  You get real music, provided you have speakers and ancillaries up to the task.  Each of Boulder’s massive 3050 monoblocks weigh 450 pounds and supply 1500 watts of Class-A power per channel, delivering an experience beyond anything I’ve ever heard.  The price tag of awesome is rarely a small one.

You also need a dedicated 220/240-volt line for each monoblock amplifier.  My wimpy 20-amp dedicated lines are not enough for me to commandeer a pair of these for review, so I go to the mountains of Boulder, Colorado, home of Boulder Amplifiers.  Forget the usual audiophile excuses about how a review can’t be written without the product being in your own system, because in this case the Boulder listening room features a pair of Focal Grande Utopia EM speakers, a model I am very familiar with.

“We haven’t sent these out for review because no one has enough AC power in their listening room to accommodate these,” laughs Boulder’s Rich Maez as we tour the factory.  And I’m guessing that only a privileged few also have floors stout enough. For those with enough power on tap and hefty floors (and the wherewithal to afford a pair), the 3050s arrive with Colorado-mined black granite bases that perfectly match the asymmetrical shape of the amplifiers.

The Epitome of Craftsmanship

The visit begins in the machine shop, where the exquisitely machined parts that make up a Boulder amplifier come to life.  Each 3050 heat sink is machined from a 115-pound solid billet of 6061-T1 aluminum alloy.  Once through Boulder’s various CNC machining centers, the amps undergo a series of final finishing operations, ending with bead-blasting and clear-anodizing processes.  As impressive as the chassis and heat sinks are, perhaps the coolest part of each Boulder 3050 is the massive power switch, which features a highly polished paddle machined from stainless steel.  It’s actuation feels like the clunk of a Bentley door.  (Click HERE to visit our website for more pictures of the Boulder factory.)

Shop foreman Ian Balmforth has been with Boulder for over 15 years, having inherited the job from his father, and he takes a tremendous level of pride in his work.  The rest of the employees in the Boulder factory share the same level of enthusiasm for their work, often putting their efforts and expertise into different phases of component production and for different models.  When orders are ready for a batch of 3000-series components, they work on nothing else until the run is complete.  Whereas so many products are built in hours, the Boulder 3050 monoblocks take approximately four weeks each to complete, from the time the raw metal enters the dock until the finished, tested and safely crated amplifiers leave.

Fully balanced, differential power amplifiers from start to finish, the 3050s offer only balanced inputs, and the driver stage consists of Boulder’s latest discrete 99H modules.  A giant metal tunnel runs through the center of the amplifier chassis, with four separate, potted transformers inside, which helps drop all mechanical and electrical noise to the theoretical minimum.

Power and Control

The Boulder 3050s have more power than anything else you can buy, but sheer watts are not the whole story.  Boulder’s president Jeff Nelson explains it as a “factor of control,” telling me that the more power available and the more devices to distribute the load—there are 120 output transistors in each 3050—the easier and more precisely the amplifier can control the movement of the speakers’ drivers and the EMF that the woofer cones generate.

Rich Maez begins my listening session of the 3050s with an introduction to the range.  Everything is driven by Boulder’s 2010 preamplifier and 1021 network disc player.  The 1008 phonostage we reviewed back in issue 27 sits on another rack with a SOTA turntable.  AC/DC’s “Rock and Roll Ain’t Noise Pollution” plays through the 800-series monoblocks (also reviewed in issue 20) with good results.  Everything Boulder is famous for is here in spades with this $12,000 pair of amplifiers:  Bass weight and control, lightning-fast dynamics and a big soundstage—impressive and duly noted.

Switching the cables to the 1050 monos and then to the 2050 monos clearly illustrates the progression.  Tonality remains the same, but each pair of amplifiers reveals more music than the models before.  Going up the range brings a lower noise floor, more weight and more dynamic jump.  And the 2050, which has been Boulder’s flagship for years, is indeed impressive, with the Grande Utopias turning in a truly grand performance.

For those not familiar with the Focal Grande Utopia EMs, they are one of the world’s finest loudspeaker systems, but their stunning level of resolution can disappoint if the rest of the system doesn’t deliver the goods, and I have heard this speaker turn in more than one lackluster performance over the years with mediocre systems.  (That’s my polite way of telling those of you who don’t like the Grande Utopias to shut your pie holes…insert smiley face.) They excel here.

Music’s New Definition

Wonderful as the 2050s are, the 3050s are a quantum leap in every aspect of performance.  Revisiting the AC/DC track is a stunning experience.  The Grande Utopias simply liquefy in the room now that the 3050s are powering them; there seem to be no speakers whatsoever, just music.  Tonality remains the same, but soundstage width and depth jumps to another level with the 3050s.  The Grandes become even more coherent, fading further into nothingness.  I’ve been listening to Back in Black since the day it was released in 1980, and I’ve never heard it like this.  The drums now have the force to convince you that you’re listening to the real thing, along with the right texture and tonality of the various drumheads.

Miles Davis’ “Freddie Freeloader” stretches out between the speakers, with natural-sounding cymbals and endless texture present in the recording; it feels as if you can hear all the way inside his horn.  This speaker-amp combo delivers a similar effect with the piano, which just floats directly out in front of the left speaker and is rendered to perfect scale, as a drumstick cracks down on the rim of the snare and Miles’ trumpet glides in so gently you don’t even notice it until the sound is there in full force.

These amplifiers deliver unbelievably tight pace and texture in the low-frequency register, regardless of volume level, again giving a feeling of being in the performance instead of just listening to it.  Acoustic bass is fleshed out perfectly, with just the right amount of resonance and texture, while electric bass growls as it should.

Unlimited Dynamics

Revving up the tempo with a dose of hard bop, Rich goes for some Freddie Hubbard, whose horn on “Philly Mignon” blows me back in the listening chair—Maxell-man style.  The complete lack of clipping or compression continues to amaze me as the hours roll by.  The opening bit to Pink Floyd’s “Welcome to the Machine” feels as if you are in an elevator 6 feet under the floor, moving up through solid matter to listening level and then up another three stories.

The bongos in Bob Dylan’s “Everything is Broken” take on a life of their own, sounding much larger than life.  While I’ve often dismissed Dylan’s Oh Mercy album as flat and uninvolving at the standard 16-bit/44-kHz resolution, it comes alive in all three dimensions in this system.  I don’t even want to listen to vinyl!

More time goes by as I investigate countless tracks that I’ve heard time and time again on many systems.  I’m continually amazed by the new experiences these amps deliver—from the Beatles to Metallica.  As Ella Fitzgerald and Louis Armstrong run through “Isn’t this a Lovely Day,” I feel as if the room’s walls are missing and the performers are walking around me as they sing.

Playing music through the Boulder 3050 monoblocks is hallucinogenic.  Continually stunned by everything I choose, I don’t want to leave the listening chair, but by now it has become dark and everyone but Maez and Nelson have long gone home for the day, so it’s time to call it a night.

Boulder achieves the ultimate with the 3050s:  They resolve more detail than anything I’ve ever experienced, yet they are never harsh or off-putting in any dimension.  As I listen to quite a few albums I am infinitely familiar with (some of which are not known for their sound quality) the music comes alive through the Boulder/Grande Utopia combination in a spectacular manner.  I’ll go on record to say that this is the most musically lifelike system, coming the closest to the real thing I’ve ever had the pleasure of listening to.

Meeting the Goal

Boulder president Jeff Nelson claims his company’s ultimate goal is to produce an amplifier devoid of sonic signature, one that lets the music come through as it may.  For this reviewer, Boulder has succeeded fantastically.  In the early 1990s, in his review of Boulder’s original 500AE power amplifiers, Stereophile editor at the time, J. Gordon Holt, said that the amplifiers “are just not there.”  Though incredible progress has been made in 22 years, this still remains the essence of the 3050s.  They truly disappear, becoming a conduit of music unlike anything I have experienced.

The paradox of the Boulder 3050s is twofold:  Hearing them will reset your bar in terms of what is possible in the world of reproduced sound, even if you only listen to average recordings.  They will also spoil you for anything else.  You don’t really need that 401k, do you?  You’ll be too old to enjoy it anyway, right?  For our readers fortunate enough to afford a pair of 3050s, I guarantee you will not be disappointed.

In addition to otherworldly sonic performance, Boulder amps come with a level of craftsmanship that is also beyond anything else I’ve experienced.  Most Boulder amplifiers produced over the company’s history are still in use, and most are still owned by the original owners.  Boulder doesn’t do “mid-model updates,” and a quick glimpse at eBay shows only a couple pieces for sale on the secondary market, and they command high prices.  (Three of the six sellers say their reason for selling is that they bought the next piece up in the Boulder line.)  I can’t imagine where you would go after owning a pair of the 3050s.

Those a little less well heeled might consider the 900-watt-per-channel 3060 stereo amplifier, which sells for $115,000.  It will still require a single 30A 240-volt outlet, but Rich Maez assures me that it offers up a very enticing experience.

Having spent plenty of time with some of the world’s top amplifiers, I can tell you that the Boulder 3050s deliver the goods.  This is not a case of paying three times as much for a miniscule increase in performance; this is a mind bender.  You’ll never be the same.

Boulder 3050 Monoblock Amplifiers

MSRP:  $205,000 per pair (including granite bases)

Boulder Amplifiers

Burmester 911mk.3

I’ve probably listened to a thousand amplifiers in the past 25 years and have easily owned at least 75-100 in search for the perfect balance of tonality, dynamics and reliability.  Proponents of every different amplifier topology have their reasons why their pet choice is “the best,” forsaking all others in the process. But the main argument usually comes down to the tube camp vs.  the solid-state camp.

While I’ve always loved vacuum tubes, I have different requirements than the average listener who may only turn on his or her system for a few hours a week.  With a reference system that is usually playing at least 12 hours a day, the tube game can get tiring in a hurry, especially when you’ve chased down some unobtanium tubes for your pride and joy.

If you’ve fallen under the spell of a great vacuum-tube power amplifier, it’s hard to wipe the experience out of your memory bank; that tonal delicacy and three-dimensional, airy presentation is indeed seductive.  It’s the same for the best examples of the solid-state camp with bottomless dynamics, weight and bass grip that you can’t get on the other side of the fence.

I’m happy to report that you can have it all in one box: the Burmester 911 mk.3.  It’s not inexpensive.  Current MSRP on a 911 mk.3 is $29,995.  If you’re anything like me, you’ve already thrown half of that price tag away over the past 10 years, swapping amplifiers in and out of your system.  A couple of thousand here, another thousand there, and pretty soon you’ve flushed a year’s worth of your kids’ college tuition down the drain. And you’re still not quite happy.  I know that feeling all too well, and I’m right there with you.

Sixty seconds to music

The 911 mk.3 couldn’t be easier to set up.  This 90-pound amplifier is covered with heatsinks on all four sides, so don’t play catch with it.  The powder-coated silver aluminum case has a pair of handles on the rear panel that makes it easy to move into place on your rack of choice.

There is a pair of balanced XLR inputs, a 15-amp IEC socket for the power cord of your choice and binding posts with gigantic plastic wing nuts that make it a snap to attach the beefiest speaker cables you can imagine.  A pair of 12-volt trigger outlets is provided to allow the 911 mk.3 to be turned on from your preamp, if it is so equipped.  I’ve never shut off the 911 mk.3 since it’s been here, so while handy, it’s not been necessary.  The front panel has a single power switch with power-on and standby LED’s.  Plug it in, turn it on and enjoy.

Built to take it

Much like the black Porsche 911 turbo in Bad Boys, the Burmester 911 mk. 3 crashed into my life.  While awaiting the delivery of the 911 and the companion Burmester 011 preamplifier, I received a phone call.  “Is this TONEAudio Magazine?”  “Yes…” “Great, I have a damaged palette that I found in the middle of the street with your companies’ name on what’s left of the label.  Give me your address and I’ll be right over.”

At this moment I was horrified that the 911mk.3 and the 011 were destroyed and my relationship with Burmester was not getting off to a great start.  Twenty minutes later, a very nice man from Northwest Gas arrived with a palette in the back of his pickup truck that looked as if it had been dropped out of an airplane.

Upon inspection, the 011 was without a scratch and the 911 mk.3 only had a slight dent in the left corner of the top faceplate.  Nothing sounded loose internally, and upon plugging them both in, they worked perfectly!  When I told Burmester’s Robb Neiman about my experience, he said “Oh yeah, we had a pair of our speakers get dropped out of the cargo plane at CEDIA this year.  They fell 30 feet and only had a tiny scratch.  They played fine.”  If this doesn’t speak volumes about the rock-solid build quality of Burmester, take a peek inside the chassis where everything is massively built and tidily tucked in place.

The essence of musicality

During the past six months, I’ve had the opportunity to use the 911 mk.3 with about 20 different pairs of speakers, all with excellent results. But the bulk of the review listening was done with the Verity Audio Sarastro II, the MartinLogan CLX, the GamuT S-7 and recently the YG Acoustics Anat II Studio.  All world-class speakers in their own right and all of them have given their best performance with the 911 mk.3.

I’ve also had about 20 amplifiers come through my listening room, either for review by me or on their way to someone else on the TONEAudio staff.  All great amplifiers to be sure, but every time I put the 911 mk.3 back in the system, I always felt like I was back home.

The best way to describe the 911 mk.3 (and for that matter all the Burmester electronics I’ve heard) is complete neutrality and complete lack of grain.  As I’ve mentioned in the 082 integrated review, everyone who has heard the 911 mk.3 always makes the comment that it does not sound like solid-state amplification, nor does it sound like tubes.  I’ve never heard an amplifier that does a better job of getting out of the way of the music than the 911 mk.3.

The bass is powerful and articulate, the mids seamless and smooth, and the highs are extended, not harsh, grainy nor forced in any way.  When working on a review of the vintage Mark Levinson no.23, it reminded me of how that amplifier had a midrange that was pushed slightly forward.  A few other solid-state amplifiers exhibited an artificial quality to the midrange or high frequencies that always left me thinking “pretty good for solid-state.”  This thought never went through my head while listening to the Burmester amplifier.

Three of my favorite large solid-state power amplifiers – the CJ Premier 350 (my previous reference for almost five years), the McIntosh MC1.2KW monoblocks and the SimAudio Moon W-7 monoblocks – each have more power than the 911 mk.3. But at the end of the day, none had the complete neutrality, lack of grain and smoothness that the Burmester has.

When playing my MartinLogan CLX’s at insane levels, I found my self wishing for a touch more power, but that was really pushing it.  Should you find yourself at that point, you can use the 911mk.3 as a mono amplifier and just add a second one.  I experienced a very similar CLX-based system that used a pair of 911’s, and that was the ticket for those who need the ultimate push over the cliff. Or perhaps the top-of-the-line 909 power amplifier …

Richly detailed

Dynamics are big fun, and so is bass grip and slam; that’s what large solid-state power amplifiers are famous for.  What continues to hold my interest so strongly after six months with the 911 mk.3 is the way this amplifier continues to unravel records I’ve been listening to my whole life on a countless variety of systems.

Even with records that aren’t known for killer sonics.  One day while stuck in an early 70’s groove, I was listening to Three Dog Night’s Seven Separate Fools CD and noticed a few layers of violins and mellotron that I’ve never heard on “Pieces of April.”  Sure, that’s a crazy music choice, but the point is that while the 911 mk.3 is an extremely high-resolution component, it is not one that sacrifices musicality for ultra detail, it blends both.  My favorite aspect of the Burmester gear is that it does not transform your system into something that you can only listen to a limited number of “audiophile approved” pressings. It brings more enjoyment to your entire music collection.

Same thing with DEVO’s Q: Are We Not Men?, A: We Are DEVO? While evaluating the original to the current remaster, this record took on a whole new dimension, with the soundstage expanding in all three dimensions.  Fast forward to current releases, “Adrien” on Peter Kruder’s (of Kruder and Dorfmeister fame) new disc, Private Collection, starts with chimes that just float slightly to the left of the soundstage, but the echoes travel all the way right and sound as if they trail off behind the listening chair.  Indeed, very trippy.

Another favorite disc that features very densely packed music is The Word is Out, by Jaco Pastorius and his Big Band.  This is a killer fusion album that has a great mix of acoustic and electronic instruments with a lot going on simultaneously.  Even at high volume, Pastorius maintains his space just slightly left of center without his bass line becoming flabby, with the drums miked somewhat behind the plane of the speakers, while the horns float in front of the mix, going all the way from left to right.

While at times almost impossible to describe, the 911 mk.3 is very linear in its performance, regardless of where you have the volume control set, until you push it so far that the soundstage flattens out, ever so slightly.  Even at this point, I wasn’t hearing any harshness or clipping.  Though the 911 mk. 3 is claimed to be heavily biased into class-A operation, it didn’t get overly warm during normal listening, and no matter how hard I pushed it, would not shut down.

I continue to draw the same conclusion with the 911 mk. 3. It has a huge, three-dimensional soundstage that I would normally associate with tubes, with the pace and drive I would normally associate with solid state, yet the weaknesses of neither.

As good as it gets

After six months of listening day in and day out, I can find no fault with the Burmester 911 mk.3 and am happy to say that this will become my new reference amplifier.  It was dropped off of a truck on its way to me and I’ve often played it continuously for 24 hours day after day when breaking in new speakers, and it’s never let me down in any way.

The 911 mk. 3 offers perfect balance in my book; it is highly detailed and articulate, yet not harsh, and it is tremendously musical without being dark or rolled off in any way.  This is truly the best power amplifier I have ever experienced.  I can’t recommend it highly enough.

The Burmester 911 mk. 3 Power Amplifier

MSRP:  $29,995


Analog source Spiral Groove SG-2 turntable w/Triplanar arm and Lyra Skala cartridge
Digital source Naim CD555/PS555    Wadia 781I   SimAudio 750
Phono preamplifier Nagra VPS w/VFS isolation base and Red Wine Audio Black Lightening power supply
Preamplifier Burmester 011    Conrad Johnson ACT 2/series two    Nagra PL-L
Speakers Gamut S-7    Harbeth Monitor 40.1    Martin Logan CLX    Verity Audio Sarastro II YG Acoustics Anat II studio

Pass Labs Xs 300 Monoblock Amplifiers

Even with a track that is not bass heavy, the Pass Xs 300 amplifiers immediately show their superiority.  Sinéad O’Connor’s luscious voice on “Bewitched, Bothered and Bewildered,” from her album Am I Not Your Girl? lingers in the air between the KEF Blades in a way that it never has before—her voice is bigger and airier, with a higher degree of “reach out and touch it” than I’m used to.  And when Michael Jackson takes us through a time warp with minimal accompaniment, courtesy of The Stripped Mixes, he truly feels right in the listening room about five feet in front of the couch.  The realism is staggering.

In the world of high-end audio, where Internet-forum pundits loudly proclaim that expensive gear is not worth the money and that its curve of performance versus diminishing returns is incredibly steep, I must strongly disagree in favor of the Xs 300s.  Having lived with Pass Labs’ $22,000-per-pair XA160.5s monoblocks for over a year, and then having stepped up to the $34,100-per-pair XA200.5s (a huge jump in performance) and now taking the leap to the $85,000-per-pair Xs 300 two-chassis monoblocks, I’m still staggered at how much more of everything is available with Pass’ flagship amplifiers.

Here in Portland, Oregon, one of America’s greenest cities, my aging hipster friends would mess themselves if they knew I had a pair of amplifiers that draw 1,000 watts each, all the time.  Okay, so I’ve thrown concerns about my carbon footprint out the window with these amps, but I do walk to work and I’ve replaced all 22 of the 50-watt halogen bulbs in my studio ceiling (along with the 15 in the house) with LEDs that only draw 7 watts each.  That just about makes up for the power that these massive monos consume.  I’d light the place with candles and eat dirt before I’d give up these amplifiers!

As TONE staff member Jerold O’Brien helps me unpack these super-sized beasts, which weigh in at 168 pounds for the power supply and 130 pounds for the output stage, we become awestruck:  The Xs 300s have six banks of output devices per channel and Pass has increased the bias current by a factor of 10 compared to the XA amplifiers.  And as Pass Labs’ Desmond Harrington is fond of saying, “This means more control.”  Interestingly enough, Jeff Nelson of Boulder Amplifiers says the same thing, and both the Boulder 3050 monoblocks and the Xs 300s are definitely the two most incredible amplifiers I’ve ever heard (for those of us who are not worried about the price tag).

Where the mighty Boulders take more of a “just the facts, ma’am” approach, the Xs 300s sound more like a gigantic tube power amplifier with tighter grip and more bass grunt, while retaining the airy character and ravishing tonality that you would normally associate with vacuum tubes.  I’d happily put the Xs 300s up against any vacuum-tube power amplifier on the market, regardless of price, and I’d still prefer them to tube power.  The Xs 300s are equally yummy, and knowing you’ll never have to forage for power tubes again is a major bonus.

Love at First Listen

O’Brien and I are both equally stunned when we begin to hook up the Xs 300s.  Way too anxious to just let one stack sit there while taking the photos for this review, we connect one of them to the GamuT S9s.  We look at each other and O’Brien exclaims, “Dude, your system sounds better in mono with one of these than it does with the pair of XA200.5s.”

Strong words indeed; this is the level of performance increase that comes with spending twice as much money with a reputable company.  If you’ve ever fallen deeply in love at first sight then you know how this is.  The Xs 300s are love at first listen.  (After months of using them with an incredibly wide range of speakers, from the $1,500-per-pair KEF LS50s to the $150,000-per-pair GamuT S9s, I’m even more smitten with them now than the day I unpacked them.)

By the time we have the photos done and the second channel connected, it’s time for some shut-eye, so the Xs300s are left to play all night, and we’ll reinvestigate them in the morning.  As is the standard procedure with massive class-A power amplifiers if they are going to be on all night, no heat is needed in the studio.

The next day’s listening session begins with a comfortably toasty listening room, but more importantly, the amplifiers are now thoroughly warmed up.  Normally, we always leave solid-state power amplifiers on 24/7, but this is just not practical with the Xs 300s, because they produce such a prodigious amount of heat.

Boxes Ticked

The amount of sheer control the Xs300s provide is unbelievable—there is truly nothing they won’t do.  When we swap out a few of the other amplifiers we have on hand for the Xs300s (even the awesome XA200.5s), it feels as if a subwoofer has been added to the system, even with the tiny KEF LS50s—which, incidentally, sound amazing through these four-box wonders.

It isn’t just all power and punch, though:  These amplifiers offer the magic of incredibly high resolution, without throwing delicate tonality out the window.  You’ll notice tasty little nuances in your favorite well-worn recordings, prompting the desire to revisit as many of them as possible.  I predict many late-evening listening sessions once you get these fully broken in.

A perfect example is Ornette Coleman’s Ornette on Tenor. This straightforward bop record features great interplay between Coleman on sax and Don Cherry on trumpet, backed up with bass and drums—a sparse mix to be sure.  The sax and trumpet tear it up across the wide stereo mix, with the drums and bass exploding from the left and right channels, respectively.  The scale at which all of this takes place, especially in the way the Xs 300s render height, makes it all sound so convincing.

The Hammond organ sounds fabulous as it creeps into the mix at the beginning of War’s “The World is a Ghetto.”  The Hammond is barely there, just skating in and out of your consciousness, but it adds an unmistakable texture to the track—all the better in 24-bit/192-kHz resolution courtesy of HDtracks.  All the while, the funky, wah-pedal-laden guitars segue in over layer upon layer of horns.  Backing up to “The Cisco Kid” proves equally enlightening.  When a piece of gear can render a track that you’ve heard way too many times and still keep you riveted, you know you’re onto something special.  This is what the top of the mountain looks like, or rather sounds like—and it’s good.  No, it’s wonderful.

Those who live and die by the sword of pace and timing will be equally enthralled with the Xs300s.  The needle in the gigantic round meter on the front panel of the amplifier chassis stays firmly planted in the center, indicating that the amp is staying in single-ended class-A operation.  Until pushed well past reasonable and prudent levels, the needle barely ever budges, as is the case when powering the 90-dB-per-watt KEF Blade speakers.

Jazzman Marc Ribot’s Silent Movies is a collection of atonal tracks that exhibit laser-sharp focus through the Xs 300s.  The decay of Ribot’s heavily processed guitar on “Natalia in Eb Major” is so realistic that I’m magically transported back to the 10th row at the Montreal Jazz Festival as I soak it all in.  As Ribot switches from distorted electric guitar to clean acoustic, the Xs 300s allow the notes to just linger in the air so that you can feel the strings resonate.

Comfortable at All Levels

Even at practically intolerable volume levels, the Xs 300s hold their poise completely, with no soundstage collapse whatsoever.  Audioslave’s “Gasoline” is by no means an audiophile darling, and it’s actually somewhat compressed; yet, on a great system this track can be unraveled.  With the meters just beginning to budge from their stops, I can feel my brain rattling around inside my head from the sheer sound-pressure level, but the pounding drums and lead guitars stay in place and Chris Cornell’s high-octane scream stays anchored, drilling itself into my being.  These amplifiers remain composed, even at these elevated levels.

Yes, this kind of listening is bad for your eardrums, but being able to pressurize your listening room at near concert levels (no matter what kind of music you enjoy) is enthralling to say the least, so use the Xs 300s with care.  A sound-level meter would be an apt accessory for these amps.

In the end, every aspect of music reproduction sounds more convincing with these amplifiers.  Pass Labs founder Nelson Pass has always been a proponent of the “first watt” methodology (i.e. if the first watt doesn’t sound great, why bother with the rest?), and he went so far as to built a pair of small power amplifiers bearing that name.  We’ve reviewed most of the First Watt amplifiers and they are superb; the massive Xs 300s manage to retain that same level of delicacy while still providing major power.  There are just some speakers with which 15 watts per channel simply won’t cut it.

Setup and Stuff

If you think you really don’t need 300 watts per channel of class-A power, think again.  The combination of speed, control and bone-crushing dynamics offers an experience you just don’t get with less power, even at low listening levels—it’s more about the control these big amplifiers provide than just power.  Incredible acceleration is an added benefit of all this power, along with the ability to stop instantly.  The Xs 300s are lightning fast with no hangover or fatigue.  They’ve been playing nearly nonstop since they arrived, and at the end of a 16-hour day I can still keep going back to the record rack for just one more.

Like the other Pass amplifiers we’ve used, the Xs300s require about 100 hours of play to be all they can be, but they are damn good straight out of the box.  Once you become intimately familiar with them, you will notice that they sound slightly hazy at first turn on, and gently yet linearly they come out of the fog over the course of about 90 minutes.  Everything just gets easier as they reach operating temperature.

Because of the heat they generate, these amplifiers need ventilation, and Pass confirms that you can stack the chassis one on top of the other, but be sure to give them plenty of room.  And if you are in tight quarters, make sure you have decent HVAC.

The Xs 300s can be used with balanced or RCA inputs, though they are fully balanced amplifiers.  The ARC REF 5 SE and Robert Koda K-10 preamplifiers work fantastic, as do the Simaudio MOON Evolution 850P and Burmester 011.  Even my vintage ARC SP-11 Mk. 2 works well, but the high resolution of the Xs 300s does reveal the limitations of this great vintage piece.  The only real downside to the Xs 300s is that you’re likely to find yourself wanting linestage and source upgrades.

A pair of enormous cables connects the chassis with the biggest Neutrik connectors I’ve ever seen.  I plug each monoblock set into a dedicated 20-amp line, even though the power cords are of the 15-amp variety—there’s no point in putting regular gas in your Aston Martin, right?  The four speaker binding posts are the super-coolio Furutech carbon-fiber jobs that ratchet tight and click when you’ve reached the proper torque, which is a nice touch.

The $85,000 Question

Though saying so may result in some hate mail, the Pass Xs 300s are worth every penny of their $85,000 price tag.  Considering a few other amps on the market that I’ve sampled, Pass could probably charge an even 100 grand for them and easily get away with it.

But you have to ask yourself a couple of questions before making this kind of a purchase decision:  Do these amplifiers take you somewhere you’ve never been before, giving you an experience that you just can’t get with a lesser product?  Are they built with a level of precision, care and attention to detail commensurate with other products at a similar price?

Yes and yes—and then some.  Fortunately, I’ve had the privilege of listening to a lot of fantastic amplifiers in the $20k-to-$40k range over the last few years, and the Xs 300s are considerably better.  They reveal more music and are more transparent, with bottomless dynamic power and they present no problem driving any of the speakers I have at my disposal.

So if you’ve got the system, the software and the scratch, buy these babies—you won’t regret it one bit.  And the couple of readers I’ve talked to who have jumped off the cliff agree with me.  These are indeed very special amplifiers.

Pass Labs Xs 300 monoblocks

MSRP: $85,000 per pair

Pass Laboratories


Analog Source AVID Acutus Reference SP turntable    TriPlanar and SME V tonearms    Lyra Atlas and Clearaudio Goldfinger SP cartridges
Phono Preamplifier ARC REF Phono 2 SE    Indigo Qualia    Pass Labs XP-25    Simaudio MOON 810LP
Digital Source dCS Vivaldi    Sooloos Control 15    Aurender S10
Speakers GamuT S9    KEF Blade    Sonus faber Aida    Sonus faber Guarneri Evolution
Cable Cardas Clear
Power IsoTek Super Titan

Pass XA160.5 Monoblock Amplifiers

No matter your drug of choice—chemical, horsepower, audio—with prolonged use, you always reach a plateau at which you believe you just can’t get any higher. But sooner or later, something else enters your reality that restarts the cycle, and you’re off and running again. Such is my experience with the Pass Labs XA160.5 monoblocks.

If you are new to the world of high-end audio, you can get the condensed history of Pass Labs here: The shorter version is simple: Nelson Pass is a genius. He’s probably got more patents for amplifier design than almost everyone else combined. And he’s got a great sense of humor, too. The owner’s manual describes the new amplifier as “tending to run heavy and hot, but elicit high performance and reliability from simple circuits.”

Weighing in at about 130 pounds each and $24,000 per pair, the XA160.5s are not for the light of wallet—or bicep. Or, for that matter, air-conditioning capacity. The power draw isn’t huge, but each unit sucks 600 watts from the power line, whether idling or at full power. Because they only produce 160 watts per channel into 8 ohms, doubling into a 4-ohm load, they get very warm to the touch. Yes, this behavior is normal for a class A design. The extra heat was welcome in March when the amplifiers arrived, as it kept our studio toasty. Yet, as days got longer, the amps forced us to run the A/C well before we normally would.

Super Yet Simple

Pass has always advocated keeping things as simple as possible. While squarely looking at the enormous monoblocks might cause you to question whether he still believes in this basics-minded philosophy, thanks to Pass’ patented SuperSymmetry design, the amplifier has only two gain stages. At the risk of oversimplifying, the SuperSymmetry approach achieves low distortion (and tonal purity) by making each half of the balanced amplifier as close to identical as possible so that the resulting distortion from each half of the amplifier circuit cancels out in balanced mode.

To achieve maximum performance, the amplifier must be run in balanced operation. Fortunately, the ARC REF 5 offers balanced and single-ended outputs, which makes comparisons a snap. And Pass is right again: Utilizing the XA160.5 in single-ended mode proved very good, but it featured a layer of grain not present in balanced mode. Whether you use a Pass Labs preamplifier or a model from another manufacturer, make sure to take the balanced route.

Coming Full Circle

My first experience with Pass’ class A amplifiers came in 1979. I combined a Threshold 400A with a Conrad Johnson PV-2 preamplifier driving a pair of Acoustats, making both an incredibly natural combination and excellent case for pairing a solid-state power amplifier with a tube preamplifier. While many combinations have since passed through my room, the tube pre/solid-state power amplifier is always the one to which I’m drawn, especially when it involves a class A amplifier.

The XA160.5s symbiotically works with all of the preamplifiers at my disposal, but the match with the Audio Research REF 5 linestage and REF Phono 2 preamplifier is heaven-sent. Pass Labs president Desmond Harrington tells me that many customers use the company’s amplifiers with tube preamplifiers. “It’s a popular combination, but when it comes to power, we like to see our amplifiers offering the tube sound without the tears.” Truer words haven’t been spoken.

As someone who’s purchased more than a fair share of power tubes, I am relieved to know that the sound of the XA160.5’s will never change. And, you won’t have to buy new power tubes every year. Continuous operation cuts down on tube life. If only Costco sold tubes by the palette.

Like Luke, I Ignored Yoda Just Once

Pass’ instruction manual cautions against using the XA160.5s with a power conditioner. Nonetheless, I plugged them directly into the wall and then into my Running Springs Maxim power conditioner, with the latter providing an even cleaner presentation. The soundstage opened up significantly, and I didn’t experience any loss of dynamics. Yes, the stock power cords that come with the XA160.5s are very good, but aftermarket power cords (Shunyata and Running Springs models yielded excellent results) offered up a slightly clearer window to the music.

In all fairness, think of superior power cords as being able to take an amplifier that goes to 11 up to 11.2. Besides, you wouldn’t put regular gas in your Porsche, would you?

Super and Scrumptious

Unlike a non-class A solid-state amplifier, the XA160.5s shouldn’t be powered on for 24 hours a day. They generate too much heat. Still, just like a tube amplifier, the XA160.5s need an hour to warm up and stabilize. At first turn on, they still sound great, but once you get used to them, you’ll notice a slight haziness that softly dissipates as the clock ticks. Coincidentally, the ARC REF 5 and REF Phono 2 need an hour to sound their best, too, so if you are using a tube front end, everything will warm up at the same pace.

I initially listened to familiar digital tracks from the Sooloos music server/dCS Paganini combination. I was immediately taken aback by the additional weight and depth, even more so with high-resolution digital files. All of the class A amplifiers with which I’ve lived share a tonal richness that other solid-state amplifiers do not possess. Some might refer to this quality as warmth, but I prefer to call it tonal richness. I associate warmth with slowness, lack of pace, and rounded-off treble; the XA160.5s exhibited none of these characteristics. The Pass monoblocks sport the equivalent of a great guitar’s ability to sustain a note. On a choice Gibson Les Paul, for example, music just seems to hang in the air a little longer.

Switching back and forth between amplifiers at my disposal revealed that the XA160.5s are indeed very special. It was as if the particular characteristics from my favorite amplifiers have somehow taken up residency in one model. Thanks to their monoblock design and huge power supplies (the 160.5 is claimed to have a significantly larger power supply than the 160 it replaces), these amplifiers throw a soundstage that is prodigious in all three dimensions. Image width really stands out.

I noticed such traits on all program material, but they became more obvious when listening to classical. Conveying the size of a symphony orchestra—much wider than most listening rooms—is one of the toughest feats to ask a system to accomplish. When listening to Sir Arnold Bax’s sixth symphony, it felt as if the sidewalls in my listening room had been each moved out about six feet. Not realistic, of course, but much more convincing than without the XA160.5s.

Recorded live and flush with ambience, Hugh Masekela’s “Stimela (The Coal Train)” from Analogue Productions’ 45RPM 2LP version of Hope provides an excellent test. Having just heard Masekela perform the song at the Montreal International Jazz Festival in June, the recorded version via the Pass amps colored me impressed. While the live version claimed a slightly different arrangement, the XA160.5s pushed my GamuT S9s to a realistic sound level and conveyed such nuance and tonal contrast, I felt like I was back in Montreal’s Club Soda venue. Even at the high volume level, the front panel’s deep-blue backlit oval meter barely flinched from its center position, indicating that the amplifier never left class A mode.

Of course, man cannot live on jazz alone. At prime operating temperature, the XA160.5s did not miss a beat on a Japanese vinyl pressing of Michael Schenker’s Built to Destroy. No matter how hard I pushed, I could not destroy the amps or my speakers. And yes, that’s a very good thing. Staying in Japanese LP mode, Bruce Springsteen’s The Wild, The Innocent, and the E-Street Shuffle proved tough to resist, as did David Bowie’s Aladdin Sane. These old favorites never sounded better, and when I quickly switched back to the gear I’ve lived with for some time, across-the-range performance boosts became manifest.

Staggering Pace and Tonality

While classical music plays to one group of the XA160.5s strengths, revisiting the recently remastered Beatles catalog plays to another: These amplifiers offer rock-solid pace. Violins in the mono version of “Eleanor Rigby” (from Revolver) were strongly anchored, and Lennon and McCartney’s voices unwavering. There was so much depth, it almost sounded like a stereo recording! Speaking of the latter, the stereo version of “Penny Lane” from Magical Mystery Tour turned out to be just as exciting. Ringo Starr’s drumming and McCartney’s bass held true throughout the psychedelic soundscape.

I am easily swayed by the big sound of these amplifiers, yet that characteristic only scratches the surface of their capabilities. Concerning tonal accuracy and texture? Spot on. Acoustic instruments sound correct, whether listening to wind, string, or percussion instruments. Dynamic contrasts equate to the best I’ve experienced. A few TONE writers whose tastes skew towards classical remain astonished at the lifelike piano reproduction.

Music fans that crave vocal performances will benefit from the XA160.5’s picture-perfect tonality and resolution. Again, the extra tonal body almost feels as if one is listening to an SET—albeit an SET with nearly unlimited power that you can use with real-world speakers. The extra low-level resolution goes a long way, especially when spinning marginal discs. An ideal example comes courtesy of Keith Richards’ Talk is Cheap. Richards is not known for possessing a terribly strong lead vocal. Yet, when put through the XA160.5s, it actually has some depth. Such is the XA160.5s’ allure. They hover at the optimum point of boasting maximum resolution without being harsh, sounding full bodied and musically natural without introducing tonal distortion— a difficult balancing act.

Bass response keeps in line with the exceptional performance found elsewhere in the frequency range. While the XA160.5s have more than ample weight and slam, the bass reveals a level of texture and detail that I’ve only experienced with a small handful of amplifiers. Remember: It’s easy to confuse “audiophile bass” (usually over-damped and distinguishable from the real thing that has life, texture, and resonance); the XA160.5’s are the genuine article. A cursory listen to your favorite acoustic bassist reveals the way these amplifiers allow the instrument to breath, and brings you that much closer to the actual performance.

Top Contenders

Two years ago, I proclaimed the Burmester 911 Mk.3’s the best amplifiers I’ve heard. And over the course of hundreds of product reviews, I’ve used that dreaded “B” word just once in the absolute sense. After conveying my enthusiasm for these amplifiers to Harrington, he responded, “The 160’s are amazing, but you need to hear the 200s.” So just when I thought I couldn’t get any higher, the quest begins again.

It’s always tough to make comparisons, yet the XA160.5 combines the virtues of my three favorite amplifiers into one (actually two) boxes:  the delicacy of the Wavac EC300B, the texture and dimensionality of the ARC REF 150, and the power, control, and composure of the Burmester 911s.

Independent of the “B” word, the Pass Labs XA160.5 monoblocks orbit the top stratosphere of amplifier design at any price. If you would like that je ne sais quoi that you thought required a vacuum-tube amplifier, these are a consummate alternative. There is nothing that the XA160.5s do not do.

The Pass Labs XA160.5 monoblocks

MSRP:  $24,000/pr.


Analog Source Audio Research REF Phono 2     AVID Acutus Reference SP w/SME V tonearm and Koetsu Urushi Blue cartridge    AVID Volvere SP w/SME 309 tonearm and Grado Statement1 cartridge
Digital Source dCS Paganini stack    Sooloos Control 15
Preamplifier Burmester 011    Burmester 088    ARC REF 5    McIntosh C500   Conrad Johnson ET5
Speakers GamuT S9
Power Running Springs Dmitri    Running Springs Maxim
Accessories Furutech DeMag    Loricraft RCM

Heavy Metal:

Everything Hans-Ole Vitus makes is heavy. Really fucking heavy. Break-your-back heavy. But those who possess the strength to lift his SM-010 monoblocks out of the boxes will be rewarded with fantastic sound. That said, it’s become very popular of late, at least in the United States, to take shots at the wealthy and, in particular, at luxury goods. So if the idea of a $40k pair of amplifiers seems offensive, let fly the invective and take a pass.

While my bias leans towards vacuum-tube gear, the finest Class A solid-state amplifiers (like the recently reviewed Pass Labs XA160.5s) offer equal palpability and don’t require having to regularly forage for tubes. Heat is the only drawback to Class A units. They are power-hungry animals, but wildlife worth feeding.

Vitus gear not only feels powerful, it looks powerful just sitting on the rack. Also available with massive red-, gold-, or black-anodized front panels, our SM-010 review samples were anodized in a stunning shade of dark gray. I’d love to see more manufacturers adopt this trend. Apologies to the Oakland Raiders, but haven’t we had enough silver and black?

Beneath the SM-010’s top panel lurks a masterpiece of modern know-how—a tidy circuit layout revealing clean electrical and mechanical design. Top-grade parts are used throughout. An enormous power transformer, custom designed for Vitus, is a work of art in its own right—and not the usual toroid that exists in most other amplifiers. Individual amplifier boards, connected directly to the circuit boards to keep signal paths as short as possible, are to the left and right of the power supply.
A solitary XLR input, along with the standard IEC power connection and two speaker outputs to facilitate bi-wiring, makes it easy to integrate a pair of SM-101s into any system. These beasts can be used as 100-watt-per-channel amplifiers in Class-AB mode or 40-watts-per-channel amps in Class A mode. With every speaker, save the Magnepan 1.7s, Class A mode yields enough power for all but the most intense listening.

Flick of the Switch

The SM-010s power up in AB mode but can easily be switched into Class A via the remote control or front panel. Yes, my inner Homer Simpson loves any adjustments that can be done from the comfort of a listening chair—it really does make the evaluation process easier. When switched to Class A, the change in the amplifiers’ performance is slightly more than subtle, acting as a tube amplifier does when switching from pentode to triode mode. Unlike all the tube amplifiers I’ve auditioned that offer this function (and make a loud ker-chunk sound when altering modes), the Vitus effortlessly and silently switches between A and AB, making sonic inspections all the more interesting. And while engaging triode mode with a vacuum-tube amplifier usually bestows more midrange lubricity, it comes at the expense of bass control. The SM-010s require no such sacrifice.

Again, like a tube amplifier, the SM-010 needs a solid hour or two for the slight initial haze to dissipate. While not green in practice, if you want to experience the best it has to offer (especially in Class A mode), leave the amps on for a day before you begin critical listening. However, prepare to see a bump in your electric bill the following month!

Listen to This

On “Hear My Train A-Comin’” from Jimi Hendrix’s recent Winterland compilation, the Vitus’ deliver the virtuoso’s distorted guitar in spades and Noel Redding’s bass playing in a way I’ve never experienced. Textures in the latter blend with the distortion, the mix growling as if emanating from the band’s vintage Ampeg amplifiers. Metallica’s so-called “Black Album” offers similar revelations when cranked up. The plucked bass line in “Nothing Else Matters” flaps my pants leg as it does at a Metallica concert. All six of my GamuT woofers work strenuously and, yet, stay controlled. I’ll trade all the string quartets in the world for five minutes of this experience, and the Vitus amplifiers grant my wishes. After a full day of seriously heavy music (that, admittedly, to the disappoint of editor Bob Gendron, did not include any St. Vitus albums), these amplifiers cannot be broken. Moreover, while they got extremely warm, their sonic character did not change.

Big solid-state power normally promises stout bass response, and the SM-010s prove no exception to the rule. Yet these amplifiers’ innate ability to unveil layer after layer of musical performances melts brain cells. If you have speakers as equally revealing as the SM-010s, you’re in for a fatigue-free experience—no matter how high or low the listening level.

Indeed, classical music aficionados will relish the delicacy with which the Vitus’ render string and wind instruments. My GamuT S9s feel like big headphones when I listen to the oboes in the Netherland Wind Ensemble’s Beethoven Wind Music. For me, texture and nuance are the chief characteristics that turn listening sessions into musical events. With the SM-010s in my system, I’m still going to great lengths to listen to records I’ve heard hundreds of times to see if I can mine new aural data.

Great amplifiers also magnify differences between mediocre recordings and standout efforts. Score another victory for the SM-010s. Used extensively in TONEAudio’s Pink Floyd coverage for Issue 40, the Vitus’ exposed subtle nuances between various Dark Side of the Moon pressings as if merely presented with apples and oranges.

Whether in AB or A mode, the SM-010s exhibit dead-quiet backgrounds with zero noise when used in conjunction with the equally silent Vitus preamplifier. When mated with my ARC REF 5 and REF PHONO 2, there’s a slight bit of tube rush—but nothing from the Vitus. This makes for a dynamic presentation, and contributes to the amplifiers always sounding much bigger than you’d expect 40-watt monoblocks to sound. They actually remind me of my favorite amplifiers from the 80s—Mark Levinson ML-2s—but boast healthier depth and detail.

The SM-010s also excel at precise acceleration and deceleration, never blurring transients. Vide, Morris Pert’s lightning-fast percussion runs in “The Poke,” from Brand X’s Masques. The amps’ perfect pace separates the percussion from the rapid-fire drumming, each keeping control of its own space. Such ability to instantaneously start and stop significantly contributes to the SM-010’s non-fatiguing sound.

Other Synergies

Partnered with my reference GamuT S9s, the SM-010s are in many ways the equal of my reference Burmester, Pass Labs, and ARC amps but, nonetheless, retain their own sonic signature. While each amplifier has its own virtues and near-faultless performance, the Vitus amplifiers thrive in their ability to resolve great detail without ever becoming fatiguing—even after full-day listening sessions.

While mixing and matching, I discovered a few synergies to be unmistakably good. For example, the B&W 802 Diamonds are completely different speakers when used in concert with the SM-010s. Normally, the 802 is very revealing and, when married to an amplifier that is either harsh or forward, mirrors the amp’s presentation. With the 802s, the Vitus sounds particularly tube-like in the upper registers, replete with the slam and control you expect from a powerful solid-state amplifier.

Heard through this combination, Keith Jarrett’s Shostakovich: 24 Preludes and Fugues, Op. 87 possesses extra depth and decay, sounding more realistic than I recall—especially on the opening “Prelude & Fugue No. 1 in C Major.” While Shostakovich is traditionally a forceful composer, this piece assumes a wistful delicacy through lesser amplifiers, as Jarrett’s light touch becomes lifeless and flat. The ultimate test? Play the composition at the low volume it demands. The Vitus passes with proverbial flying colors.

B&Ws aside, the oddest albeit most interesting combination I experienced with the SM-010s occurred with the compact Penaudio Cenya speakers. Most people would not mate a $40k pair of amplifiers with a $4,000 pair of speakers, but hey, why not give it a try? The Cenyas sounded supercharged, disappearing in the room as never before, almost as if a subwoofer entered the equation.

Not Just Another Brick in the Audio Wall

Some audiophiles argue that speakers are everything to a system, while others, maintaining the garbage in/garbage out theory, believe the source the most important link in the chain. I feel every part is equally important. But I’ve also seen plenty of astonishing speakers and fantastic source components humbled when lacking proper amplification. Truth be told, I’ve heard modest speakers deliver performances I never thought possible when a standout amplifier drives them. So, at the end of the day, I’m an amplifier guy.

A pair of Vitus SM-010 amplifiers will present no compromise to your system no matter the quality of your other components. These behemoths may even inspire you to make a few improvements once you get used to their abilities. While the price is high, it’s commensurate with the level of build and sound quality. Think of the SM-010s as an ultimate audio destination—desert-island tracks optional.

Vitus Audio SM-101 Monoblocks
MSRP: $40,000/pair
Manufacturer Information:


Analog Source AVID Acutus Reference SP/SME V/Koetsu Urushi Blue

Phono Preamplifier ARC REF Phono 2

Preamplifier ARC REF 5, Burmester 011, Vitus SP-101

Digital Source dCS Paganini Stack, Sooloos Control 15

Speakers GamuT S9, Verity Amadis, B&W 802 Diamond, Magnepan 1.7

Power Running Springs Dmitri, Maxim PLCs, RSA Mongoose Cords

Cable Shunyata Aurora SP

Accessories SRA Scuttle Equipment rack, SRA Ohio XL equipment bases, Furutech DeMag, Loricraft LR-4 record cleaner