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Positive Feedback ISSUE 18
march/april 2005


audio zone

Amp-1 integrated amplifier

as reviewed by John Acton






ProAc Tablette Reference 8 Signature (primary) and Quad 11L l (secondary).

Bryston B60 SST and Audio Zone Amp-1 integrated amplifiers.

SimAudio Moon Nova CD player.

Analysis Plus Solo Crystal Oval interconnect (1 meter, RCA), Analysis Plus Oval 9 (bi-wire, 8 feet), Custom Power Cord Company HCF 2 Special (CD player), and Custom Power Cord Company HCF 2 (amp).

ASC Tube Traps in front corners (5 feet tall; 16" diameter) and ASC Studio Traps (2) behind equipment rack on front wall.


Prejudice is a strong word, one that does not possess a positive connotation. Prejudice is stronger than mere bias, and few (if any) of us can state categorically that we are free of or inured to it. I'm not referring to large social issues like race, religion, or sex, but to the everyday prejudices that plague us as consumers. We harbor prejudices against retailers, automakers, clothing designers—the possibilities are endless. Prejudices drive us toward or away from something as intangible as an idea or as concrete as a product, based upon our (or others') previous experience.

Prejudice applies to the world of audio as much as it does to anything else. Of course, everyone has his or her own likes, dislikes, and personal biases (tubes vs. solid state, analog vs. digital, dynamic vs. planar, etc.), but when we refuse to consider a product or a technology without having experienced it, prejudice rears its ugly head. What am I saying? Simply that I have my prejudices. A case in point: I'm prejudiced against horns because of my exposure to Cerwin-Vega loudspeakers during my formative years. Have I listened to other horn speakers? No. Is this wrong? Probably.

Another of my prejudices brings me to the subject of this review, the Audio Zone Amp-1 integrated amplifier, which employs op amps. I've been a music lover and audiophile for years, and one of the things I've heard so many times that I have had no choice but to believe it is that discrete components are always preferable to integrated circuits. When the Amp-1 arrived, my prejudices were in full bloom. Would it have enough power to play music with anything resembling dynamics and transparency? Or would it sound compressed, murky, and congested? I couldn't shake the transistor-radio images that my mind was conjuring up as I stared at the small (but surprisingly heavy) box sitting on my floor. Unfortunately, unpacking the diminutive Amp-1 did little to allay my prejudices. To be fair, however, the amp was packed very well.

The Amp-1 is contained in two small boxes. One chassis contains the power supply, comprised of a heavy-duty Plitron toroidal transformer, and the other comprises the amp itself. The black metal case of the power supply has an AC inlet, two Cardas cords for connection to the amp, and the on/off switch for the amp. The amp is no bigger than a typical car stereo amp, but is very well built and quite attractive. Done up in silver (the power supply can be had in matching silver for additional cost), with a thick faceplate and back plate, the unit is constructed in two discreet halves that visually emphasize its dual-mono construction. The front of the unit contains two gold-colored knobs for control of volume for the left and right channels, in 31 steps. The back contains two inlets for the left and right power supply feeds, high-quality Cardas RCA inputs, and a pair of high-quality, gold plated, five-way binding posts.

That's it, folks—utter simplicity. One source input and no remote control. Despite its solid build and attractive appearance (gold cone feet complete the package), the amp still resembles a toy, especially in comparison to some of the behemoth amps I've had in my system (Bryston, Pass, Levinson, etc.). Internally, only top-notch components are employed (Black Gate capacitors, Riddick resistors, Cardas wiring), and this high level of quality is combined with an incredibly short signal path (120 mm from input to output), all of which is said to provide unsurpassed transparency and directness. The output is 45 watts per channel into 8 ohms (100 peak watts). No distortion figures are provided. Gain is 30dB, and the signal-to-noise ratio is 95dB.

So how did it sound? I followed the manufacturer's recommendations and let the Amp-1 burn in for 150 hours before any serious evaluations. Fresh out of the box, the little Amp-1 sounded kind of thin, with a forward midrange and watered down, anemic-sounding bass. The soundstage was foreshortened, and dynamics constrained. The amp sounded, well, small, but there was promise. From the get-go, I was taken with its immediacy, transparency, and speed. It drew me into the music right away, leading me to hope that additional burn-in would flesh out its undernourished bottom end and add some body and size. I also noticed how dead silent the amp was. Putting my ears to the tweeters of my speakers, I had to strain to detect any noise. I've never experienced that kind of silence from any amplifier before, tube or solid-state. I did hear some transformer hum from the power supply, but it was never objectionable, and was only noticeable from close up. The amp runs so cool as to question whether it's on.

As the amp burned in, the bottom end fleshed out, the soundstage expanded, and the dynamic envelope burgeoned. What didn't change, however, was its already extraordinary levels of transparency, for the price. If I had to choose one word to describe the sound, it would be "open." The Amp-1 presented such a clear window to the heart of the recording and the music contained within that it was captivating, even addicting. The Amp-1 is so communicative, so direct, that it doesn't encourage background listening. Quite the opposite—it seems to say, "There's some good music happenin' here, Mac, and you WILL pay attention." It was very easy to pick out individual instruments or voices from overproduced rock recordings. The Police's Synchronicity (A&M 069 493 599-2) is one example, even in its recent remastering, but through the Amp-1, Sting's voice was more palpable, more present, more tonally "there" than I've ever heard it. Likewise, Stewart Copeland's drum playing was highlighted, as if Windex was applied to the recording. The amp provided a clearer window to his snare and cymbal work, accenting his outstanding contribution to the music.

The Amp-1 imbues recordings with a level of sheer immediacy that, once experienced, is hard to live without. Tangerine Dream's soundtrack to Firestarter (Varese Sarabande VSD-5251), while not a terrible recording, is slightly murky. The Amp-1 cleaned it up, and let me hear all the way back into the recording. It allowed me to get to the heart of the music. Let me clarify, however, that this immediacy was not accompanied by brightness. The treble was very neutral, exhibiting no grain or solid-state texture that I could detect. Neither, however, was the top end typically tube-like. Bright recordings were exposed for what they are, and any lack of air was likewise passed right along. But when things were good, they were very good indeed. The cymbal work on Steely Dan's remastered Aja (MCA 088 112 056-2) was very convincing, with no graininess or edge. The Amp-1's transparency and openness allowed Donald Fagen's voice to appear in three dimensions above and between my speakers, with holographic realism. I've never heard Wayne Shorter's saxophone sound so immediate, so urgent, on the title cut. And did I mention the speed? The Amp-1 captures and lets go of transients with blinding speed, but never with hyper-realistic exaggeration. It sounds extremely clean, which complements its all-around transparency. Dom F Scab’s well-recorded electronic album Facta (Groove Unlimited GR-077) pulsed across the back wall of my room with dynamic realism. Imaging and soundstaging were also well rendered, with superb focus and terrific depth. Tube fanatics and owners of large solid-state amps may find the soundstage to be a little small, but I found nothing to gripe about.

What about the downsides? There are a few. (No amp is perfect, eh?) The Amp-1 is not a high-current megawatt design, and this manifests itself in two ways. First, according to the manufacturer, the amp is not happy with low-impedance speakers, nor is it at its best with speakers that have multiple drivers and/or complex (i.e., power hungry, current-drawing) crossovers. I did not have the ability to test this, as I use small, easy-to-drive speakers (Quad 11Ls and ProAc Tablette Reference 8 Signatures), but I take the manufacturer at his word. Second, the Amp-1 does not represent the ultimate in bass extension and slam. While the bass was extremely tight, fast and controlled, it did not evince the warmth of a tube amp or the slam of a high-powered solid-state behemoth. Since the Amp-1 was not designed for loudspeakers the size of import cars (they know who they are), this shouldn't be a critical issue. Also, a couple hundred hours of additional burn-in may improve this aspect of its performance.

The Amp-1 is voiced slightly on the forward side, so those looking for a liquid or laid-back presentation should look elsewhere. But for those who want an amp that conveys the emotion, the immediacy, and the sheer essence of music, the Amp-1 should be on their must-audition list. Lastly, from a purely operational standpoint, the stepped attenuators make it more difficult to find just the right listening level than it would be with a linear volume control.

What about comparisons? My reference amp for some time has been the Bryston B60 (the latest revision, with SST output devices). The B60 is a great amp. I prefer it to more expensive (and much more powerful) competitors like the Krell KAV-400xi (slightly opaque in the midrange and less involving) or the Plinius 9200 (too laid back—very smooth, but not as dynamic and exciting). The B60 is very transparent, doing less damage to the signal than most amps at or near its price range, and it possesses great dynamics for its power rating. When I compared the B60 and the Amp-1, it quickly became apparent that they sounded quite different. The Bryston was smoother and warmer, but the Amp-1 was much more transparent. Switching from the Bryston to the Amp-1 was like cleaning a window that I didn't realize was dirty. The Amp-1 did a better job of drawing me into the music than the Bryston—a tall order, as I consider the Bryston to be outstanding in that regard. The B60 does have greater bass impact and extension. Despite the Amp-1's claim to fame regarding dynamics, I found both amps to be fairly equal in this regard. Forced to choose, I would say that the Audio Zone may be a touch better, but I can't be certain. Soundstaging was also a tough call. The Bryston, with its dual-mono construction (including power supply) presented a larger, stronger central image, but the Audio Zone ha a slightly more delineated soundstage, with better separation of images and greater depth of field.

In conclusion, I circle back to my opening paragraph on the topic of prejudice. In my experience with the Audio Zone Amp-1, I learned a valuable lesson: Don't judge a book by its appearance, or by the type of paper that it contains. I was overwhelmed by the openness, transparency, immediacy, and musicality of this diminutive amp. In many ways, it has provided the best sound I've experienced to date in my system, and for a very reasonable price. I've never before felt myself get so drawn into the music. The Amp-1's qualities have become so addictive that I can no longer bear taking it out of my system, even to do comparisons. Okay, so there's no remote, there are two volume controls and only one input (though the manufacturer does make an adaptor for multi-source users). These things may rule this amp out of consideration for a lot of music lovers, but I urge them to reconsider. If they can look past these minor quibbles, what they will see is an amp that has a world-class ability to bring the musical performance to life. The Amp-1 has forced me to re-evaluate my other prejudices. I'm willing to bet that it would be a perfect match for a pair of easy-to-drive horns. John Acton

Audio Zone Amp-1
Retail: $1995

Audio Oasis
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