Zesto Audio Leto Preamplifier

Sonic Magic

Equipment report
Tubed preamplifiers
Zesto Audio Leto
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).