Zesto Audio Bia 120 Stereo Power Amplifier


Equipment report
Tubed power amplifiers
Zesto Audio Bia 120
Zesto Audio Bia 120 Stereo Power Amplifier

Imaging? Holographic. Moreover, there is something so preternaturally spacious about the reproduction it may constitute a subtle coloration, though if so, it’s a very attractive one. Put on really well recorded orchestral music, like any of John Eargle’s on Delos, for example, and the impression of size, scale, bloom, and vastness is spine-tingling indeed. The same is true for intimate music: I’ve been enjoying the Balcea’s traversal of the Beethoven quartets, which are very naturally recorded with a good recital hall’s row G-M perspective—close my eyes and the ensemble is simply there in the front of my room. This held for LP after CD after SACD after high-res download. A litany of examples would serve no purpose than to make the same points over and over again.

I used the Bia on my Quads, the lovely Harbeth Monitor 30.1s, the fabulous new MartinLogan Montis (review forthcoming), and it acquitted itself superbly on each. My experience with the Montis is limited, but I have long experience with my Quads, and can truthfully say I’ve never heard them sound better. This is the proverbial match made in heaven (and scarcely less so with the Harbeths).

Is the Bia perfect? Well, of course, nothing’s perfect, but no matter what I threw at it, I couldn’t make it sound anything less than beautiful. There may be some other amplifiers that can beat it out for sheer crunch and slam at the bottom, but I’ve no way of evaluating this because I don’t own speakers with very large woofers that may need that kind of control. Current tastes run for more zing, zip, spit, and sizzle up top, though not mine, as I find these things inaccurate and often irritating— sounds the Bia seems incapable of generating. And yet, I know that there is something about the reproduction here that isn’t truly accurate. The complete absence of any sort of negative feedback practically guarantees output impedance on the high side or, equivalently, a damping factor on the low, and this always has an adverse affect on flat frequency response into real-world loads, i.e., speakers. Despite listing a full set of specifications, the Bia’s flyer does not state the figures for output impedance and damping factor, which, in my opinion, Counnas was remiss not to have measured and published.

But listening reveals the effects all the same. My favorite recorded performance of Appalachian Spring is Bernstein with the New York Philharmonic on Columbia. There are many sonic virtues to the reproduction, including powerful dynamics and a clear recording of great spaciousness. But it is multi-miked and notably bright, even fierce throughout the presence region and the highs. On most modern systems, which tend to have rising top ends, the sound can be fatiguing. On a truly flat system, the sound is tolerable, the violins not shrill, but not far off shrill, and in any case have way too much sheen and brilliance. (Every piece in this all-Copland collection is a great performance, but owing to the sonics, I rarely listen to more than one at time.) With the Bia, however, it’s a whole other story. Though the reproduction is plainly bright, it is so smooth and polished, still brilliant, though now silkily brilliant, as to be not only very listenable but even rather wonderful (think of a somewhat overexposed photograph that you manage to correct in Photoshop or Lightroom). It’s pretty hard to be a stickler for absolute accuracy when a component lets you enjoy one of your favorite recordings more than you ever have before.

I’ve already pointed out that the highs are never edgy or hard, which is good, but neither do you have the kind of crystalline ring, ultimate sparkle or tingle, or even the pleasing bite much high percussion can have. This extends to some other instruments too. Sonny Rollins’ sax on Way Out West (SACD and vinyl reissue) is rendered with fabulous body and richness, and even the requisite bite and edge that his tone by design has, yet it still lacks the last degree of those latter qualities I hear from amplifiers that I know to be more literally accurate. I am told this is perfectly consistent behavior from an amplifier that has a highish output impedance. (Harbeth 30.1s have a more extended high-frequency response than either the Quads or the MartinLogans, so they and the Bia are really quite witchy together.)

I should not want to overstate any of this, as the Bia stays within what I would consider acceptable bounds of overall neutrality. But those who love rock and roll, some kinds of jazz or percussion, or any other music that depends for its full effect upon a certain degree of grunge, grit, and rasp would surely want to audition before buying. But, then, you’d have to be crazy to buy any tube amplifier before auditioning, because the spectral profile will always vary somewhat with speaker load in a way that it does not with most solid-state amps.

So where does that leave us? Can a component sound too beautiful? Is accuracy overrated? These aren’t questions anyone can answer for anyone else, so personal is the decision. So many recordings are miked so close to the musicians as to sound at best unnatural and at worst aggressively awful (this is one reason why I still value tone controls, especially for the treble). A design like the Bia poses a real conundrum when it comes to the truth or beauty question. A very close friend of mine, an audiophile of four decades standing, used to love tube electronics and acquired quite a collection of them. Eventually, and in part for professional reasons, he sold them in favor of components that would form a true reference system that would tell him what recordings, including those he makes himself, actually sound like. I invited him over to hear the Bia—he is very familiar with the sound of my system—and his face broke into a smile within just a few minutes. “I can see right away why you’ve fallen in love with this thing; it’s so damn beautiful, so luscious and...velvety. I was in love with sound like this for years, though of course in those days it was nowhere near as clean, low-distortion, or quiet as this, and with nothing of the bass reproduction.” Well, there it is: I freely admit to having become quite besotted with the Bia.

Regular readers of mine will know that judged on the basis of performance alone, I do not find super-expensive electronics to be worth the prices asked for them. By this I don’t mean that they’re not good, merely that they do not in my judgment offer sufficient performance over their lower-priced counterparts to justify the stratospheric asking prices, and sometimes they offer no improvement at all—and we happen to be living in a time of unprecedentedly high performance in even budget-priced electronics. By comparison to the pricing of the most expensive electronics, which can cost as much as luxury automobiles, the Bia’s $12,500 retail is positively modest; but it could be called a bargain only in the crazy world of high-end audio, where wire costs tens of thousands of dollars. By most people’s standards, including mine, it’s still very expensive (another four or five grand gets you an economy car!), and much more than I can justify paying for an amplifier, especially when there are so many available for much less that are more literally accurate.

That said, truth in reporting also requires me to add that the Bia is the only amplifier costing more than $10k that I’ve heard that I might actually consider buying for the sheer love of the way it makes almost every recording I have sound beautiful. It’s not the only amplifier I would ever want to own, especially for reviewing purposes; but if I did own it, I know it would get a lot of use and never cease to be a favorite. This is the kind of design around which passionately enthusiastic cults form, and I can easily see its owners treasuring it like classic Marantz or McIntosh amps from the salad days of high-end audio. I certainly would.


Power output: 60Wpc, 20Hz–50kHz +/-1dB
Speaker outputs: 4, 8, 16 ohms
THD: 0.22% at 1W output into 8 ohms
Gain: 23dB
Noise level: <0.2mV RMS into 8 ohms with input shorted
Tube complement: Matched quad set of four KT88s; four Gold Pin ECC 82s (12AU7)
Dimensions: 17" x 20" x 10"
Weight: 66 lbs.
Warranty: 2 years amplifier, 6 mos. Tubes
Price: $12,500

Thousand Oaks, CA
(805) 807-1841

Featured Articles