Decware Zen Mystery Amp

Edgar Winter’s They Only Come Out at Night was the first record in my collection, so to say I’m intimately familiar with it would be an understatement. For old times’ sake, it’s the first album I place on the turntable when critical listening begins for the Zen Mystery Amp (ZMA). Wow! Just when you think you’ve heard it all and you know a piece of music inside and out, this amp whacks you upside the head—which is enlightening and it’s what keeps this reviewing game interesting. The first cymbal crash on Radiohead’s “High and Dry” further convinces me that I’m listening to something magical. There’s more air and delicacy everywhere. The ZMA is all about nuance and finding more information lurking in the details.

This is one of the most musical, most natural, most realistic amplifiers I’ve ever had the pleasure to live with—and it’s been with me for the better part of a year now. If you want to call BS, be my guest. (I’ve got my flame-retardant Kevlar suit on, so take your best shot.) After a crazed life of audiophilia and now 12 years of covering high-end audio as my day job, I still haven’t heard an amplifier that sounds more musical than the ZMA. My Pass Xs 300 monoblocks are on the short list, as are the Audio Research GS150 and Conrad-Johnson LP120SA+. Compared to the ZMA’s 40 watts per channel, all three of those amplifiers have more power on tap, making a wider range of speakers in larger rooms a possibility—but the sheer musical purity of the ZMA is tough to ignore, for a number of reasons.

Arf, Arf

Ever meet a small dog with a big soul? A 20-pound critter with more bark than a German Shepard or Saint Bernard? That’s the ZMA. I’ve always felt that you need a big amplifier to get big sound, but the ZMA not only plays damn loud for only having 40 wpc on tap, it has a ton of headroom. When it does clip, it does so in such a gentle manner that you’ll only notice a slight collapse of the soundstage, rather than sounding like you’ve just hit a sonic brick wall.

If you can live within the ZMA’s performance envelope, there is no reason to buy anything else, even for something two or even 10 times the price. The Holy Grail is right here, built proudly in Illinois. It only takes a brief listen to the ZMA to realize that the only mystery is how Steve Deckert can build an amplifier like this for $5,695 and still stay in business. If this piece of audio fine art had a Shindo or Wavac badge on the front, it would easily have another zero on the price tag. Take it from someone who’s owned both: Save the dough and buy American. The ZMA is a better amplifier than either—and it carries a lifetime warranty and tech support (for the original owner).

If the $12,000 Zen monoblocks are out of reach, or you just don’t have room for a pair of amps (albeit compact ones), the ZMA is essentially the same amplifier on one chassis, with a smaller power supply, delivering 40 wpc compared to the 60 wpc that the monos produce. I’ve been using the Decware Torii for the last few years and my only complaint is that I find myself wanting just a little more power. Even though the Torii is the little amp that can, there are times when 26 wpc just isn’t quite enough. In every way, the ZMA brings more to the table than the already excellent Torii, but above all things, it brings finesse.

Details, Details

It’s up to you whether or not God is in the details, but regardless of what you believe (or don’t) in the spiritual department, I submit that musical happiness does indeed lurk in the details. Happiness in the form of musical engagement is, for me, an experience that keeps you riveted to your listening chair, digging one record after the next, searching for those favorite tracks that, once you’ve heard them through the ZMA, have you searching for more. After several months, this still happens every time I fire up the ZMA.

Regardless of the tracks chosen, subtlety abounds with this amp, and it continually offers little surprises on so many records that I’ve been listening to for years. And listening to new music is equally dreamy. Trent Reznor’s soundtrack for the recent movie Gone Girl is so good it’s scary, constantly reminding me of the tension in the film. Reznor is known for his ability to build a dense and ethereal soundscape—and the ZMA, combined with the GamuT RS5 speakers, envelops me in so much more than what I might call a soundstage with another amplifier. The ZMA creates a hyper-real, three-dimensional sound sphere. While a record like this does not provide the picture of musical accuracy that your favorite Blue Note might, it does have many layers of minute detail—and through a less-capable amplifier, those details just don’t come through in the same dreamy sonic picture that the ZMA paints.

Tracking through well-known albums from Brian Eno and Jean-Michel Jarre prove equally ethereal. Jarre’s Zoolook features a track, “Diva,” with what sounds like water droplets behind layers of synthesizers, with Laurie Anderson saying something in reverse over the top. Trippy as this is, each layer breathes in its own space and, through the ZMA, Anderson’s voice sounds as if she’s just been let out of an asylum; it’s scary-movie good.

Sounding this good on surreal music, the ZMA excels when the fare turns to acoustic instruments. All of the texture, attack and decay associated with piano, guitar, drums and other acoustic instruments are revealed with shocking clarity. As a photographer, I can only describe this effect by saying its similar to going from a standard-definition picture to HD, and even to the latest 4K. The ZMA presents more and smoother steps of gradation, resulting in bongo drums sounding like actual bongos. There’s cheese and then there are cheese-like substances (i.e. Velveeta). Once you hear a piano or violin reproduced through the ZMA, it will be tough to go back to what you’d been using. As Bob Stuart at Meridian likes to say, “When you’ve heard it right, you can’t unhear it.”

The upper registers of the ZMA are as close to perfect as can be. Cymbals not only have the required meat, they have proper texture and decay. The same can be said for the lower register, which are even tougher for a tube amplifier to get right. Again, the ZMA succeeds brilliantly, producing low notes with tone and texture but also with the proper amount of speed and damping, without being overly damped. A picture may be worth a thousand words, but five minutes of actually experiencing the ZMA might well be one of the biggest “a-ha” moments I’ve had in high-end audio.

Setup and Further Listening

The ZMA arrives packed in a padded Pelican Case, with the tube complement in another box. Following the well-documented instruction manual will have you up and running in no time. Even after running the amp for a month, I didn’t have to rebias the tubes; and now after more than six months, they’ve required just a tiny adjustment to stay perfectly biased and matched to each other. Unlike with some tube amplifiers, the ZMA allows you to set each KT66 tube individually and does not require matched output tubes. It’s also worth mentioning that Decware encloses a power cord with the ZMA that a lot of other cable guys would nick you an extra thousand bucks for.

While the ZMA has two sets of binding posts, one for 4-ohm speakers and one for 8, Decware does offer an option that can power 8- or 16-ohm speakers—which leads to my only complaint with the ZMA: The high-quality binding posts are too damn close together. It’s tough to tighten them down onto fairly thick spade lugs like mine—but I will say that you can use banana plugs with ease.

Inputs are single-ended RCA jacks, with XLR inputs via Jensen 95khz transformers available as a $600 option. As Deckert points out, “while not a fully differential balanced circuit, it is still a tehnically balanced amplifier – and the transformer is your friend. It gives a beautiful shimmer to the top end and better dimensionality not unlike a great moving coil cartridge.” I must agree. Using equal lengths of Cardas clear via the XLR and RCA inputs, I do prefer the balanced inputs.

Those with only one source component who want to bypass the preamplifier can tick the stepped attenuator box for an additional $150. Should you fall in this category, this is the perfect shortcut to creating a highly resolving system on a tight budget (unless you have a world-class preamplifier—but then you’re probably not on a tight budget).

A bit of research on the Decware forum reveals that its claim of long tube life is no scam. Even after years, many Decware users are still running their original set of tubes! The 6N23P input tubes can be swapped for 6N1Ps or 6922s, but Deckert says the 6N23P is his favorite, and my experience is to follow his lead. While I leave the input and regulator tubes as installed from the factory, the tube swapping goblins do possess me to try a set of NOS Siemens EL34s in place of the KT66 tubes. The sound is just different, with the E34s being a little warmer and a little softer than the KT66s. Those liking a low-end that is a bit softer, flabbier and less controlled may prefer the EL34s, but I happily went back to the KT66s. Neurotic tube-swapping in my Torii led me back to what Deckert suggested in the first place, so from now I just listen to Obi-Wan.

However, I do believe the combination of 0A3 regulator tubes, fast recovery solid-state rectifiers and 4,500 uF of power supply capacitance is a big part of the ZMAs exquisite sound. This is way more power supply than any 40-wpc tube amplifier needs, or is supplied with any other similarly powered tube amplifier I’ve seen pass through our listening rooms. The ZMAs large, well-executed power supply translates into dynamic capability, a low noise floor and the ability to execute wide transient swings with ease.

Deckert has told me that his amplifiers just keep sounding better, as the wire in the output transformers becomes seasoned over the years. My experience with the Torii has been similar. After 100 or so hours of what audiophiles might consider “break-in,” this amplifier just keeps sounding more natural. The same is happening with the ZMA and I’m sure the person who ends up with our review sample will enjoy it even more in five years than I am today.

We mate the ZMA to some insanely expensive speakers: Focal Stella Utopias, Dynaudio Evidence Platinums, KEF Blades and now the GamuT RS5, as well as the Dali Epicon 8. All have a sensitivity rating between 87 and 89 dB and work well at modest to somewhat loud volumes. In my large listening room, I’m able to run the ZMA out of juice when going for fairly loud listening levels, but for most users in a more reasonably sized room, you will have to tax this one to get it to clip.

In my smaller room at more reasonable listening levels, the GamuTs, Egglestonworks Emmas (which were on our cover last issue) and a vintage pair of Acoustat 2+2s prove absolutely heavenly with the ZMA. We use Cardas Clear cable throughout and every speaker we test happens to work best on the output impedance setting that matches the factory rating.

The ZMA sounds great at turn-on, and while it takes longer to fully warm up than other tube amplifiers I’ve used, the transition from cold to warm is more gradual than any other tube amplifier I’ve used. Again, it’s that gradation thing.

This is the point where many reviewers make wry comments about how they will miss said review product dearly, and in regards to the ZMA, I must admit to having similar feelings. However, I’m looking at this more as an au revoir (since I’m saving for a pair of Zen Monos for my retirement.)

The ZMA is more than worthy of one of our Exceptional Value Awards. Considering the level of sound quality and build quality it offers, the ZMA is one of the most exceptional values I’ve ever encountered.

Decware Zen Mystery Amp

MSRP: $5,695


Analog Source AVID Acutus Reference turntable SP/SME V tonearm    Lyra Atlas cartridge
Phonostage ARC REF Phono 2
Amplification Robert Koda K10       Audio Research GSPre    Pass Labs Xs 300 monoblocks
Digital Source dCS Vivaldi four-box stack
Speakers Focal Stella Utopias    Dynaudio Evidence Platinums    KEF Blades    GamuT RS5    Dali Epicon 8    Egglestonworks Emma     Acoustat 2+2
Cable Cardas Clear
Power IsoTek Super Titan

Decware Zen Torii Mk.3 Amplifier

Hyundai covers its engines for 100,000 miles. Bryston guarantees its amplifiers for 30 years. Decware guarantees its amplifiers for life. Any way you look at it, offering long warranties takes guts. It also means you better make a damn good product, or you’re going to go broke servicing warranty repairs.

The Decware Zen Torii Mk.3 is a damn good amplifier.

While I hate to use the “b” word (best), the Torii is my favorite power amplifier based on the EL-34 tube, and that’s saying a lot. I’ve always had a major affection for such amplifiers, which possess many characteristics of great single-ended triode amplifiers and yet, have more power and control than an SET can muster.

Think of the Torii as an SET with benefits—namely, increased bass control and dynamics. Unless you have extraordinarily efficient speakers, a few watts per channel just won’t rock your world. But 25 watts per channel dramatically changes the game, and is more than enough to power the Verity Audio Amadis speakers (93db/1-watt sensitivity) to a sufficiently high level on music of any kind. The Mk.2 does a fine job with the Verity Rienzis (87db/1 watt) and B&W 802 Diamonds (90db/1 watt). Still, the Amadis’ added sensitivity is just what’s needed to push the envelope.

Decware owner and chief engineer Steve Deckert claims his amplifier is “the last one you’ll ever want” and should only be used with a preamplifier if you happen to have a world-class unit at your disposal. Fortunately, I have two: An ARC REF 5 (vacuum tubes) and Burmester 011 (solid-state), each reference components, and both excellent matches for the Torii. At the end of the day, with the Verity speakers, I was willing to relinquish the last bit of the ARC preamp’s front-to-back-image depth for the additional bass grip and slam the Burmester provides. With the GamuT S9s, the ARC has the edge.

An optional $150 stepped attenuator on the Torii makes it easy to keep the preamplifiers used within their respective sweet spot, balancing dynamics and the lowest noise floor in the presentation.  While the sound remains excellent when using the dCS Paganini straight into the Torii, via the Paganini’s digital volume control, I feel that a killer linestage brings maximum dynamics to the table.

Deckert warned me that the Torii would require a long break-in period. Yet it sounded good right out of its supplied Pelican Case—another nice option, and one that certainly beats a cheesy cardboard box. Moreover, it keeps improving over time and, if I had to guess even after 700 hours of listening time, still sounds as if it is advancing. Where many amplifiers sound grainy and two-dimensional after only a few hours on the clock, the Torii’s tonal character just keeps ameliorating as the hours rack up.

My review sample has the optional V-Cap upgrade, which adds $500 to the window sticker. It’s well worth the price. A custom wood base is also available, meaning that a completely tweaked-out version fetches about $3,600. Each Torii is hand-built by one person and given plenty of attention from start to finish, not unlike a master engine constructed at Ferrari or Aston Martin. Such care becomes obvious the minute you take your Torii out of the carton; it’s truly a product to cherish. (Decware products are all built to order and only available factory-direct.)

Rolling, Rolling, Rolling

The only aspect that might drive you nuts with the Torii? The amount of customization you can bring to its sound by swapping various tubes. This amplifier is what a tennis ball is to a Jack Russell terrier; you can chase it forever and you’ll collapse in exhaustion by the time you’re done. If that’s your idea of fun, you’ll never get bored with the Torii. While every tube makes a difference, the output tubes seemingly make the least amount of difference. I tried several combinations, but the input tubes and voltage regulators provide more sonic variance than swapping output tubes.

Deckert attributes this characteristic to his “Hazen grid modification” that involves substituting a non-polarized film capacitor for the piece of wire that normally connects between the suppressor grid and cathode in the output stage. Deckert also touts another benefit of his modification: The basic push-pull output stage makes it less sensitive to tube type. I must concur. This is great news—especially considering that the price of vintage NOS EL-34 tubes can soar as high as $300 each.

The Torii comes with the most informative owners manual I’ve ever seen. Rather than bore you with paragraphs of tube rolling escapades, click here for the manual:

And the adjustments don’t stop with the tubes. You can choose one of two bias settings, and there is a bass and treble control. Not traditional tone controls, mind you, but two more ways to optimize the speaker/amplifier interface. The treble control rolls off the high-frequency response of the amplifier, but simply shunts to ground so it is not in the signal path. Deckert says the “bass control” actually impacts how the amplifier interacts with the speakers, and that there is no fixed “flat” position for these controls. Hence, they must be adjusted with each speaker. Finally, a 4/8-ohm impedance switch is present and, as with any tube amplifier with multiple output taps, should also be sampled, as often times the best match is not what you might think.

Those who stay focused and have the Zen-like patience to settle on a combination (or two) will be rewarded with a presentation that transports them to a special place. Even if you stick with the supplied tubes, the bass, treble, bias, and impedance controls are worth five minutes of your time. Consider: the Torii might actually save you money if you’ve got a pair of speakers that are too forward or a touch boomy. There’s a good chance that making small adjustments will dial in a speaker you may have considered selling. More money for concert tickets never came easier.

Unlike Any Other EL-34 Amplifier

Whereas a Shindo or vintage Marantz amplifier embellishes the sound in a way in which the music tends to sound warm, romantic, and even a bit slow regarding pace and timing (not that this is always a bad thing for many digital and other less-than-stellar recordings), ultimately laying resolution on a sacrificial altar, the Torii strikes a perfect balance of rendering additional tonal richness without altering the music’s fundamental character.

Via the Torii, Moraine’s “Uncle Tang’s Cabinet of Dr. Caligari” from Metamorphic Rock is an absolute prog freak-out, with layer upon layer of maniacal synthesizers and overdubbed guitars all kept in order with larger-than-life drums. Whatever your taste in complex tunes—be it prog, metal, or full-scale orchestral music—you will find intoxicating the Torii’s ability to maintain musical pace.

Without fail, the Torii consistently digs deep into recordings, uncovering morsels of information you may have never heard before. Montrose’s “Rock Candy” is a classic example of a slightly flat recording that comes alive with this amplifier. Usually devoid of any soundstage depth, drums and guitar became invigorated, assuming their own space while lead singer Sam Hagar’s voice remains front and center. And a phenomenal recording like The Band’s Music From Big Pink takes on a life of its own, feeling as if it’s mixed in surround.

The trick the Torii plays better than most vacuum-tube amplifiers stems from its ability to achieve an astonishing balance between tonal richness and tonal purity. And it does so without sliding down the slippery slope of coloration and euphonic distortion. Acoustic instruments retain correct timbre, complete with a fine-grained decay that seems to fade out forever.

Moreover, while most pure tube amplifiers exhibit tube rush when no signal is present, the Torii has none. Chalk it up to the unique utilization of the voltage regulator tubes. The Torii uses them in series, working as active filters rather than in parallel to regulate voltage. This approach also puts almost no stress on the tubes. Unsurprisingly, Deckert claims the latter should practically last the life of the amplifier. While I still notice modest improvements when plugging in to my Running Springs Maxim power line conditioner, the Torii exhibits less improvement than any other vacuum-tube amplifier I’ve plugged into the Maxim. It’s another test that further confirms Deckert’s claims.

Sure. Watts are watts. But thanks to its robust power supply and proprietary output transformers, the Torii has an abundance of headroom and very gently extends past its peak power output, with barely a hint of clipping. Even when playing the heaviest metal, the amplifier always feels bigger than its modest power rating suggests.

All of this adds up to sound reproduction that is rare with most amplifiers, no matter the price, and a practical miracle at $3,600. Granted, 25 watts per channel won’t be optimum for every speaker and room combination. But within this realm, I can’t think of a more enjoyable amplifier than the Decware Zen Torii Mk.2. I bought the review sample and plan on keeping it long enough to see if it will ever break.

One last word to the wise: Those wanting to put a Torii under a Christmas tree should get on the phone now. Orders are currently subject to a 10 week wait. Deckert told me that they have a backlog of 90 to build right now, and hopefully by spring they will be back to the standard 4-6 week wait.

Decware Zen Torii Mk. 3

MSRP: $2,945-$3,700 (depending on options)


Analog Source AVID Acutus Reference SP/SME V/Koetsu Urushi Blue
Digital Source dCS Paganini stack     Wadia 581i     Sooloos Control 15
Preamplifiers ARC REF 5    Burmester 011
Speakers B&W 802 Diamonds    Verity Rienzi    Verity Amadis    GamuT S9   MartinLogan ElectroMotion ESL
Cable Cardas Clear
Power Running Springs Maxim PLC    Running Springs Mongoose cords