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Zesto Audio Leto Preamplifier

Zesto Audio Leto Preamplifier

The Leto preamplifier, a linestage that is the second product of George and Carolyn Counnas’ Zesto Audio, is cut so completely from the same sonic cloth as Zesto’s Andros PS1 phonostage I reviewed last year that describing its sound would be to repeat more or less what I said then (Issue 222). Like the Andros, the Leto is an all-tube design that represents what I often call classic tube sound brought up to date. By this I mean that it boasts all the roundedness, dimensionality, and body that we love from classic tubes without their wayward tonal anomalies, their deficiencies at the bass end, and their relatively high noise levels. The overall tonal balance is neutral—it allowed, for example, all the differences among the pickups in my upcoming cartridge survey elsewhere to be revealed unambiguously—though my initial impression was that it might be fractionally on the warm side. With extended listening, however, I am much less certain of this because, as I observed of the Andros, the really distinguishing characteristic of the Leto is a wonderful freedom from the usual sorts of sonic hype and electromechanical artifacts. It’s the absence of such artifacts that sometimes tricks the ear into hearing warmth simply because the presentation is so free from anything potentially irritating. (No wonder the Zesto rooms have turned up so often on the “best sound” lists of recent audio shows.) It is transparent enough that transparency needn’t be a concern, detailed enough that resolution isn’t a worry, and fast and incisive enough to do full justice to The Rite of Spring, For Duke, or The Sheffield Drum Test Record. But if you demand that every transient come off like a pistol shot, you might want to look elsewhere: a naturalness that soon becomes quite addictive is the order of the day with this preamplifier, though it is also lively in its dynamics and lifelike in its vividness and vitality.

The Leto’s distinctive cosmetics constitute a visual correlative to its sound, especially as regards its very low background noise (this even without the usual “for a tube unit” qualification): all graceful silver curves and subtly rounded edges against black, matching those for the Andros (Carolyn Counnas the stylist for both). Although the exposed tubes render stacking impossible, they certainly make a striking duo placed side by side. This is one pair of components you don’t want to hide. The front panel sports three identical knobs that control volume, source, and balance, and two LEDs labeled “mute” and “mon” (for mono). The diminutive handset—which does not require line of sight to do its job—controls volume, mute, and mono or stereo operation, with balance and source-selection available only at the chassis (my sole functional complaint that balance is inaccessible from the remote, but at least there is a balance control). Three inputs are single-ended, two balanced; there are a total of four pairs of outputs, two single-ended and two balanced. (There’s also a “cinema-bypass” circuit.) As on the Andros, two back-panel toggle switches, one for each channel, float the ground if necessary; another switch bypasses the handset, a thoughtful touch inasmuch as muted output is the default upon turn on, which would otherwise leave you no way to get it unmuted if you happen to misplace the handset.

Fit, finish, quality of parts, and build are identical to the Andros, which is to say of very high standard; the Leto is hand-assembled; and it comes already broken in for fifty hours. Operation could not be simpler or more straightforward: Hook everything up where things obviously should go and flip on the side-panel rockerswitch, being careful to heed the manual’s warning of amp on last/off first, otherwise you’ll get a thump through the speakers (it will likely damage nothing, but it is disconcerting). Although the four tubes look identical at a casual glance, they are not: If you need to replace or remove a tube, be sure to return it to the same socket from which it was taken.

Since I am using the Andros and Leto combination for much of my moving-coil pickup survey, where the sound of the combination is implicitly described, I am here going to concentrate on digital sources so as to give a better sense of the linestage’s intrinsic characteristics apart from the phono preamp. (I assume it goes without saying but I’ll say it anyway: Just because Zesto makes an outstanding phono preamp of its own doesn’t bind you to use it with the Leto—you can use any high-quality stand-alone phonostage.) I started with the Dorati Firebird on SACD, still for all-around rhythmic impetus, punch, drive, and dynamism, not to forget lyric expressiveness, the finest performance and recording known to me (including the composer’s own). After all these decades it remains a bonafide audiophile masterpiece and one of Mercury’s signature achievements. Yet, like most Mercurys, it is also to my ears somewhat brightly lit, so I was eager to hear if the Leto might soften in it any way. Not at all: As with every other neutral component or setup through which I’ve heard this recording, strings are a little more brilliant than real but with a lots of sheen. Brass too have some bogus brilliance, which is also attributable to the recording, but also are reproduced with really lifelike timbre with no undue sharpness or edge, rather like the difference between a photograph that is naturally sharp and one that has been oversharpened in Photoshop.

The densely scored passages are thrillingly rendered: clarity and blend in equal and just proportions and climaxes that land with tremendous force and crunch. I want to reinforce this last observation. Tube units, even modern ones, for all their warmth and romance, are generally thought to be a little on the soft and/ or “slow” side compared to transistors and to lack an impression of real strength. But I am astonished at the sense of sheer power the Leto is able to convey. Offhand I can’t think that I’ve heard the big moments of this recording reproduced with a greater impression of occasion in my system. And don’t for a moment think, “tube bass,” when it comes to the Leto. Bass drums, tympani, trombones, tubas, bassoons, doublebasses have truly prodigious weight and definition. As for the goings on way up high, well, the big passages open out as impressively as they land, with extraordinary air and bloom. The Leto handled the plangent closing pages of the piece magnificently, with massed brass soaring gloriously above strings, tympani, and bass drum: I’ve rarely heard it bettered, even when it comes to ultimate loudness—indeed, I wouldn’t want it any louder in my room, and my Quads were capable of going a bit louder. While I’m doling out praise for power, let me not slight the Quad 909 amplifier and 2805 speaker, neither of which components is supposed to have particularly strong bass or wide dynamic range. Sure glad no one told my units!

Given what I heard from the bass on this recording and most others, I remain surprised there is so little impression of added warmth, particularly since the unit is specified flat to only 10Hz. Theoretically, this means there must almost certainly be some phase shifting going on higher in the bass range, but, as with Quad 909 amplifier, which rolls off near the same frequency, the effects seem entirely benign. They might also be more in evidence with a woofer that goes very deep in the bass, as opposed to my Quad panels (though their 6dB point is actually in the mid-thirties). I point this out only by way of suggesting that if this is a concern of yours, you should audition accordingly (but then you know you should do that anyhow).


The entire midrange is beyond criticism, which I ascertained with the Anonymous Four’s Gloryland SACD. As I’ve said in other reviews, this is a real acid test for midrange resolution of fine distinctions in vocal character. The Four aim for the greatest possible blend, yet their voices are still subtly different from one another, which a revealing system will let you hear. A good cut for assessing this is the gospel hymn “Where We’ll Never Grow Old,” where the girls (no disrespect here—this is how they refer to themselves) are spread across the middle two-thirds of the soundstage, set back slightly, so that you hear a fair amount of air, but are still very present and slightly staggered front to back, so you should hear some depth between them. “Palmetto” opens with a solo singer who is joined by the group for the second verse, but here they are clustered even closer together and in a line, so there shouldn’t be a wide stereo spread and the soloist should sound clear of the others. Their blend is again little short of unbelievable, yet individual timbres are still perceivable with close listening. Another reason this recording is a reference of mine and why I was especially interested in hearing it through the Leto is that the sound is unusually pure and cold: There should be no “warmth” as such, but rather a cold, even chilly beauty. The Leto aced this SACD on every talking point without breaking a sweat.

The top end? Airy, extended, and natural. Listen to any recording that has really well-captured atmosphere or lots of high percussion and any concerns about the darkness that you’re supposed to find in tube units—and do in some—are immediately banished. Almost any jazz ensemble will do, or something like Christy Baron’s cover of “Mercy Street” on Steppin’ (Chesky SACD), which has, among other instruments, a rain stick on it. On The Christmas Revels, you can actually hear the sound ricochet off the walls so clearly that you can almost measure the size of the venue, while the collection of period and folk instruments will tell you volumes about a component’s ability to differentiate timbre and tone color. Again, the Leto’s handling of all this is second to none other’s.

One question the Leto raises is why electronic components that measure essentially ruler-flat, as this one does, should still sound different from one another, and sometimes not all that subtly. The only thing that occurs to me, and this is especially to the point when comparing tubes and solid-state, is differing harmonic-distortion profiles. Still after all these years, tubes distort differently from transistors, generally more pleasantly—even-ordered harmonic distortion as opposed to odd. Sometimes audiophiles want still more of tubes’ distinctive distortion because it’s so pleasing (hence the cults that develop around single-ended-triode amplifiers). The Leto’s specified distortion is so extremely low that experts I’ve consulted find it hard to believe it could contribute anything of consequence to the reproduction. But what little there is, perhaps because it remains tube in origin, may be responsible for a difficult-to-define impression of texture about the presentation that accounts for that organic quality I noticed in the Andros and hear in the Leto as well. I realize that this may contradict what I said earlier about freedom from sonic hype and electronic artifacts. So be it. Whatever the explanation, it results in a musicality and an impression of realism that are at once valid and authoritative yet without ever stepping outside the boundaries of sonic neutrality.

Subjective reviewing does not allow for components to be evaluated in isolation because the evaluations must be based on listening. Every now and then, however, components come along that serendipitously combine with other components so as to make for very special synergies that we clumsily call “magical.” This is what happened when I put the Leto into my current system, the amplifier and speaker complement of which consists in a Quad 909 amplifier and Quad ESL 2805 speakers (connected with AudioQuest interconnects and Kimber speaker cables, with a WyWires power cord). The Leto and 909 amplifier share similar characteristics of being unusually free from electromechanical artifacts and having vivid and engaging midranges, a full bottom end (the 909 very slightly on the warm side of neutral), and completely natural top ends. Their presentations also have an unusually high degree of body and dimensionality to them. The Quad 2805s are vanishingly low in coloration; state of the art for “speed,” transparency, and clarity; standard-setting for neutrality, openness, and that elusive sense of lifelikeness. I freely admit that when it comes to ultimate loudness and very deep bass-response, they are not only challenged but fall considerably short for some tastes or in rooms very much larger than mine. That granted, however, roll them all together and you have a system I could live with happily and never feel the need to make any changes for a very long time. I used other amplifiers throughout the listening sessions, and the fine qualities of the Leto were evident no matter what it was partnered with. But there was something that kept pulling me back to the Leto/909 combination, especially with the Quad ESLs: sonic magic indeed.

One of the last things I played before wrapping up the review is the DG “Originals” reissue of William Steinberg’s sensational recording of The Planets, musically and sonically one of the most dramatic performances of Holst’s suite, with a ferociously menacing realization of “Mars, Bringer of War.” When the cut ended, my six-year-old daughter, who had never heard it before, said, “Daddy, that music was scary. Please don’t play it again.” Samantha doubtless would have responded the same way if she had heard it on any good or better system. But I like to think her response had at least something to do with the sense of engagement, involvement, and sheer vitality the Leto brought to the system. I removed The Planets and put in Peter, Paul, and Mary’s album of children’s songs, which brought a smile to Sam’s face, though not before she asked me to program out “Puff, the Magic Dragon,” because, she said, “It makes me sad.”


Frequency response: 10Hz—100kHz, +/-1dB
Inputs: Three single-ended, two balanced
Noise: -100dB
Dimensions: 17″ x 5″ x 12″
Weight: 23 lbs.
Price: $7500

Zesto Audio
Thousand Oaks, California
(805) 807-1840


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