Conrad-Johnson MF2550 SE Amplifier

The generally accepted wisdom is that tube amps display a warm sound while solid-state amps offer more punch and control. But those lines are blurring, with great designs in both camps that defy past assumptions—and this is where Conrad-Johnson comes to mind. Compared to the company’s legendary valve-based gear, its MF2550 power amp takes a different approach—namely the fact that it’s solid state. The amp is available as a standard or special-edition (SE) version, the latter of which is priced at $7,800 and includes CJD Teflon hybrid capacitors and precision foil resistors. We did not have the opportunity to test these two versions side by side, but considering the outstanding performance of the SE version, it’s likely that the standard version is no slouch.

The MF2550 is rather nondescript and traditional in its appearance. The black metal chassis, which measures 16.25 inches deep, 19 inches wide, and 6.125 inches tall, features a faceplate made of thick aluminum with gold anodizing and a brushed-matte finish. Among my other black and silver audio components, the amp’s gold color—a signature of CJ—certainly stands out. The only feature interrupting the smooth faceplate is a power button the size of a quarter on the lower right corner. A gentle yellow LED halo illuminates the button when pressed. The only thing distinguishing the special-edition amp from the standard version is a small plate on the back of the unit that notes the serial number and the SE designation.

Connecting the amp could not be easier, with a set of RCA inputs and the requisite speaker binding posts; it takes only two minutes and a little finger strength to get the amp up and running. I appreciate the amp’s five-way metal binding posts, which effortlessly handle a post wrench. The posts easily accommodate two-banana adapters and offer plenty of space to connect spades and even bare-ended wire.

Pushing the gold-colored button to reveal the sonic prowess within, I first wonder if the amp is on, since it is silent. Even the ribbon tweeters in my Piega P-10 speakers do no hiss at the visiting power source.

Hidden Treasure

Much of the amp’s 52-pound weight comes from the hefty power supply fueling 250 watts into 8 ohms, or 500 watts into 4 ohms. On paper, the MF2550’s power output is a dead-ringer for my Mark Levinson reference amp, so it’s exciting to swap in the CJ. There are indeed many similarities between the two amps, as well as a few key differences.

Three-dimensional presentation is a dramatic strength of this amp. Music appears independent of the speakers and audible in all directions. Left-to-right imaging extends the music well beyond the speaker boundaries, with a very convincing central image. The amp also pinpoints other musical elements across the soundstage. Front-to-back layering leaves the vocalist up front, while allowing ambient background sounds to extend beyond the rear wall of my listening space. There’s no perceived vertical limitation either, as the music extends from floor to ceiling. On Lyle Lovett’s song “Church,” from his Joshua Judges Ruth album, the background vocalists are rendered well behind Lovett, who appears front and center. While my reference amp is quite good in its ability to layer musical elements, the CJ exceeds it.

The MF2550 takes command of my speakers with deep, rich and robust bass. Compared with my reference amp, the MF2550’s bass response is not quite as tight and punchy. Rage Against the Machine remains one of my guilty pleasures. The band’s song “Bombtrack” provides a good reference point for bass. Through the CJ, the bass portrayal is not loose or lacking depth, though there’s just a touch less immediacy and excitement compared to my Levinson.

Throughout my listening experience, there’s a very slightly warm tendency to this solid-state amp, which I wasn’t expecting. To be clear, the CJ does not overly romanticize the sound; it’s just a bit more forgiving than I’m used to. There’s a slight gentleness when listening to recordings that usually prove overly revealing. I’m able to turn the volume up higher for an immersive music experience without any hard-edged notes piercing my eardrums. At first, I wonder if some higher frequencies are rolled off, but after testing several frequency sweep tracks, all the highs are there. The CJ’s design just manages to somehow take most sting and vocal sibilance out.

Some live instruments can have an inherent bite. During live performances, it’s never pleasant to be in the blast zone of a trumpet, saxophone, snare drum, or cymbal crash. Nevertheless, that experience is the reality of the music. Through the CJ’s portrayal of music in my own system, while subtle, there’s just a touch less detail and realism. For instance, the sonic decay of the cymbal on the Dave Brubeck Quartet’s “Blue Rondo à la Turk” subsides more quickly than I’m used to. At the same time, the Civil Wars’ “Dust to Dust” on vinyl proves an utterly opulent experience. Minute sonic details aside, it’s easy to find oneself immersed in the emotion and beauty of the song.

I would not call this amp euphonic, but it leans to the side of forgiving musicality, as opposed to pure realism. Is this a bad thing? No. On a sunny day, many folks prefer to tame the glare with sunglasses, right? Similarly, if your system is a bit bright for your taste, or if you just prefer a portrayal that’s a tad relaxed, the MF2550 may provide the balance you’ve been looking for.

The Golden Ticket?

I thoroughly enjoyed the month I spent with the MF2550 SE in my system, as did several of my friends who regularly come over to listen. The MF2550 SE is something I could enjoy happily for a long time. On vocally driven performances, jazz and orchestral pieces, the CJ leaves little to desire. For those who prefer rock music with all its inherent aggression and vigor, the CJ stands more toward the polite end of the spectrum. In all cases, though, the musicality of the performance shines though.

With plenty of power and a non-fatiguing presence, this amp will likely pair well with many speakers and components. It certainly plays nicely with all my test equipment. Given its $7,800 retail price, the amp represents a long-term investment for many audio fans, but many rewards come with it.

Combining great sound with substantial build quality and a three-year warranty on parts and labor, the MF2550 SE could be something that you find at the end of your quest for sonic treasure. If these benefits sound compelling to you, definitely make a run to your local Conrad-Johnson dealer and hear for yourself what this amp can do.  

Additional Listening

By Jeff Dorgay

While so many audio enthusiasts think of Conrad-Johnson as a strictly vacuum-tube company, the brand has made some very impressive solid-state amplifiers over the years. The benchmark that comes to my mind is its Premier 350, which served as my reference amplifier for years. So when Lew Johnson told me about the MF2550 SE, this was the immediate comparison floating around in my head. But Johnson was quick to point out that the MF2550 SE is a “completely different amplifier” that would really surprise me.

And surprise it does. Thanks to a bevy of CJD Teflon capacitors, the ones that have been highly influential in the sound of CJ for the last 10 years or so, the MF2550 SE has a thoroughly modern sound. Bringing back my Premier 350, along with CJ’s ACT2 Series 2 preamplifier, makes it easy to compare and contrast the two amps.

Overall, the MF2550 SE has a very dynamic, extended sound. Those of you who remember the company’s early solid-state amplifiers and who did not experience the Premier 350 will be stunned at just how spectacular this new amplifier sounds, especially considering how well CJ is known for vacuum-tube amplifiers. The overall tonality is highly natural, with barely a hint of warmness. It’s not quite as neutral as, say, the top-of-the-line Simaudio Moon amplifiers that we’ve listened to or the Premier 350, but it’s not as warm as my Burmester 911 MK3 or the Pass XA series amplifiers.

Running the MF2550 SE through its paces with a wide range of speakers, including the Focal Maestro Utopia, Dynaudio Evidence Platinum, and even my old Acoustat 2+2s, reveals that this amplifier will drive any speakers comfortably, with power to spare. Whether rocking out with AC/DC, or relaxing with a string quartet, this amplifier presents a wide, deep soundstage and a level of nuance and control usually associated with a much more expensive amplifier.

As with the Premier 350, Conrad-Johnson’s MF2550 SE’s simple, elegant, and understated design delivers breathtaking musical performance in a compact package. And, as someone who has owned quite a few CJ products over the last 35 years, I will say that the Champagne-colored faceplate is just fine by me.

MF2550 SE amplifier

MSRP: $7,800


Digital source JRiver Media Center 19    Light Harmonic DaVinci DAC    Audio Research CD3 MK2
Analog source SME 10 turntable     Dynavector 17D3 cartridge
Preamplifer Coffman Labs G1-A
Power amplifier Mark Levinson No. 335
Cables Jena Labs interconnects and Twin 15 speaker cable
Power Running Springs Audio Haley    RSA/Cardas Mongoose power cords
Accessories ASC Tube Traps    Cathedral Sound room-dampening panels    Mapleshade Samson racks    Coffman Labs footers

Vienna Acoustics Mozart SE

Vienna Acoustics takes pride in doing things somewhat differently than the rest of the pack.  Most manufacturers refer to their SE models as “special editions,” yet the new Mozart is a “Symphony Edition.”  A nice touch.  Also, whereas many speakers utilize a ring radiator or metallic dome of some sort, Vienna chooses a 1.1-inch silk dome tweeter, produced to the company’s specs in the Scan-Speak factory.

“We kept the front faceplate from a standard Scan-Speak tweeter to keep cost down,” says Kevin Wolff, Vienna Acoustics’ International Sales Director.  “But inside, it’s all different.  We pushed for a handful of design changes to make this tweeter really special.”  And special it is.  The tweeter is the same one used in the $6,500-per-pair Beethoven Concert Grand speakers and, like those pricier models, the $3,500 Mozart SEs redefine “sweet spot.”

A visit from Wolff underlines just how good these speakers are and how critical it is to fine-tune speaker placement.  The Mozarts sound great right out of the box, but 20 minutes of careful fine-tuning takes them from great to sublime.  Think, for a minute, how your car’s ride is affected with one tire underinflated.  The crisp steering response you’re used to is diminished, but a quick trip to the air pump makes a substantial difference, making things right again.  It’s the same with speaker placement.  Once the Mozart’s are right, they disappear in the room like a great pair of mini monitors, but with a much more robust LF response.

Satisfied that things are performing properly, we audition a number of different tracks.  At the end of our listening session, the MoFi LP of Marvin Gaye’s Let’s Get it On makes its way to the turntable and Wolff smiles.  The Mozarts definitely have the juju, revealing the magic of the Lyra Atlas cartridge—quite impressive for any speaker, but even more so considering their reasonable price.

Comfortable Playing Everything

The ultra-wide stereo effect of Lou Donaldson’s LD+3 immediately captivates, accentuating the improved sound of the Audio Wave remaster, as well as the timbral accuracy that the Mozart SEs bring to the presentation.  While we can blather on about crossover slopes and the like, suffice it to say that everything works together brilliantly—in seconds you forget such tedious technical details and concentrate on the music.  Gene Harris’ piano sounds wonderful and Donaldson’s sax commands the soundstage.  The Mozart’s simply let the music shine through, leaving you to just enjoy rather than analyze.

Students of PRaT (Pace, Rhythm and Timing) will be instantly smitten with the Mozart SEs.  Changing the pace from classic Blue Note jazz to the title track of Frank Zappa’s Jazz From Hell is equally fascinating.  The Mozart SEs do not miss a lick of Zappa’s rapid time changes and dissonant textures.  Donald Fagen’s new release, Sunken Condos, provides a calm middle ground.  The highly textured and stylized studio recording illustrates how well the Mozart SEs effortlessly keep everything sorted.

Don Henley’s “Not Enough Love in the World,” from his album Building the Perfect Beast, is similarly rendered.  This slightly compressed, over-processed and totally ’80s classic divulges new treasures.  Henley’s voice has major depth, combined with layer upon layer of synthesizers—you can almost feel someone bending the pitch wheel on that Yamaha DX7.  Leaving this ’80s genre for some heavier tunes proves an important point about the Mozarts:  They give a riveting performance of less-than-primo recordings, an important consideration for those of us living in the real world.

U2’s Rattle and Hum has to be one of the most poorly recorded live albums in history.  But, when cranking up “All Along the Watchtower” to what has to be the Mozarts’ breaking point (the meters on the ARC REF 250’s pushing close to the “caution” zone), the speakers handle it effortlessly, proving that these are not speakers limited to only a handful of audiophile-approved pressings.  In the midst of this gigantic ball of midrange, you can distinctly pick out the Edge’s backup vocals over the distorted guitars and throttling bass line.  The Mozarts are clearly just as comfortable playing it casual or formal.

The review wouldn’t be complete without playing a bit of the music for which these speakers are named—and Kathleen Battle performing “Motet; Exsultate, Jubilate, K.165” (from Kathleen Battle Sings Mozart) adequately fits the bill.  Battle’s pure soprano gently fills the soundstage, going rapidly up and down the scale.  Here, speakers lacking the Mozarts’ transient speed would blur horribly.  Again, the Mozarts maintain the pace perfectly with complex fare, even at low volumes.  The speakers realistically reproduce the violins while still giving more than enough weight to the orchestra.

Moving into a heavier and more-modern realm of musical selections, I was impressed with the level of bass output of the two 6.5-inch drivers.  A long playlist of electronica and hip-hop tracks proves that these speakers are only limited by the accompanying amplifiers’ power reserve.  Deadmau5’ “Right This Second” from the 4×4=12 album goes down very deep, forcing the Mozart SEs to move a serious amount of air, which they handle impeccably.  Before bouncing back to Daft Punk, a quick interlude of Pink Floyd, Genesis and Mickey Hart confirms the speakers’ major bass output.

Labeled a 2.5-way system, the speakers are equipped with two woofers, which handle the deepest bass tones and combine the speed of smaller drivers but have the output of a single larger one.  The lower driver gently rolls off as frequencies rise, offering the pinpoint imaging and low upper-bass coloration of a mini monitor.

Beautiful Inside and Out

Relying on gentle crossover slopes and wideband drivers, the Mozart SEs achieve a 90-dB sensitivity rating and are tremendously easy to drive.  Crossover capacitors are matched to 1% tolerance and the inductors to .7%.  You’d expect this kind of fanaticism in a $20,000 pair of speakers, but it’s unheard of in a $3,500 pair.  “We only know how to build a speaker one way,” Wolff says with a smile, as way of explanation.

The cabinets of these beauties are equally sumptuous yet understated.  The radius on the front baffle is hand-finished—the piano-black finish puts the paint job of an S-Class Mercedes to shame.  The binding posts are unique to Vienna Acoustics, and they’re not those dreadful plastic-coated binding items that so many manufacturers have adopted.  Even the front grille takes a different approach:  The crease down the middle helps to channel tweeter energy, in “all but the most critical listening situations,” according to the company.

The drivers are VA’s own design, assembled at the Scan-Speak factory, and it’s worth noting that the woofers show an equal level of obsession on behalf of the manufacturer.  The company utilizes its own X3P composite, which can vary in consistency to the intended application, so these are far from being off-the-shelf polypropylene cones.  The transparent cone used for the Mozarts has become a VA design cue, blending visually into the design of the black speakers.

This extreme attention to detail reminds me of when Porsche introduced the first water-cooled 911.  Comedian and freelance Porsche spokesperson Jerry Seinfeld commented on the “density of thought” that goes into the manufacturing of Porsche automobiles. Similarly, in sea of mass-produced speaker systems, the Mozart SEs exude quality, regardless of how far you dissect them.

Sure, the bigger VA speakers play louder and go deeper, but the sonic quality of these speakers is tremendous for $3,500.  The Mozarts prove a phenomenal match for the new Primare I22 integrated DAC/amplifier that Wolff happens to have on hand.  (A full review of that piece of gear is in the works.)  At $2,499, the Primare is an awesome match to the Mozarts, as are the various other reasonably priced amplifiers we have at our disposal.  Yet, when connected to a full complement of ARC reference components, the speakers deliver even greater performance, well beyond what you’d expect for $3,500 a pair.

Pick Your Finish

You can get your own pair of Mozart SEs in Rosewood, Maple, Cherry or the Piano Black that our review sample arrived in.  For an additional charge, a stunning Piano White is also available.  The beautiful finishes of these speakers serve to remind that, in a world where a $20,000 price tag is more common than not, it’s refreshing to find a pair of $3,500 speakers that are built with the same level of care and attention to detail as those with a five-figure price tag.

The Vienna Acoustics Mozart SEs combine musical accuracy with dynamic ability in a compact and stylish package.  They are not only worthy of one of our Exceptional Value Awards for 2012, they are one of the best speaker values this writer has encountered in a long time.

Vienna Acoustics Mozart SE loudspeakers

MSRP:  $3,500/pair (cherry and piano black)  $3,850 (rosewood and piano white)


Analog Source VPI Classic 1    Lyra Kleos
Preamplifier ARC REF 5SE
Phonostage  ARC REF Phono 2SE
Power Amplifier ARC REF 250 monoblocks    Pass XA200.5 monoblocks  Pass Aleph 3    Prima Luna Dialogue 6 monoblocks    Carver VTM20, Primare I22 (integrated)
Digital Source  dCS Paganini    Wadia 121    Sooloos Control 15    Aurender S10   Wadia 171 w/iPod Touch
Cable Cardas Clear