This review page is supported in part by the sponsors whose ad banners are displayed below

Dionysos. Compared to even my $2.000 Bent Audio Tap-X passive with its 61-step autoformer volume—54 steps below unity gain, 6 above it invoking transformer stepup gain—Thrax's far coarser control was very limiting. In a system with 4V balanced source, 10-watt amps of 1V input sensitivity or higher and standard 91dB speakers (Metrum Hex, FirstWatt SIT1, Aries Cerat Gladius), the Bulgarian had perhaps seven steps before it got too loud. Forget high-efficiency speakers. With such behavior it approximated a completely illegal car which jumps from 0 to 10 to 20km/hr. Good luck parking or driving it. For a machine of such elevated price I found this a very peculiar compatibility restriction.
Compared to Nagra's €10.700 Jazz with its motorized Alps pot, I heard no advantages I'd lay at the feet of Thrax's TVC. Even at 12dB gain the Jazz with its very finely calibrated taper demonstrated what achieving precisely desired signal strength ought to mean (and its 0dB gain mode expanded the intermediate value range yet further). My seating position relative to the source stack has remotes hit components from about 45° or more. Here Nagra's wand was far more responsive too. Thrax's caused routine misses. On baseline functionality this audition started off on the wrong foot. On sound the Thrax competed directly against the more affordable Jazz though it was endowed with less of its textural virtues which in that review I'd summarized as suppleness, fluidity and succulence. The Thrax was the more lit up and energetic on leading edges. In that, fascia layout and remote it very closely mirrored my Tap-X passive. Despite knowing of the signal-path 6N6 triode whose active gain contributions I very rarely tapped, the Dionysos sonically acted very much like a pure passive in fact. The operative term was crystalline. By costing so much more, I was of course keen to hear what exactly the Dionysos did that would recommend it over my John Chapman unit beside balanced i/o ports, ground-lift switches and a sculpted fascia fit for a modern art exhibit.


The first difference was noise. With the Tap-X in an otherwise front-to-back Thrax stack*, I had a small ground-loop hum. This contradicted Rumen's claim that their fully isolated circuitry is immune to such things. The second difference was expected. The readout for the same level showed 27:7, giving the Tap-X that many more useful steps. The third difference was substance. Perhaps because it was impedance compensated or perhaps because it runs an active voltage gain stage, the Thrax sounded more robust. Without diminishing any brilliance, clarity, tacit immediacy or being lit up top to bottom, it clearly had superior body. This rendered the true passive whiter and paler by comparison as though—trekkie alert—it hadn't completely beamed down yet.
_____________________________________

* My iMac couldn't see the Maximinus when connected USB direct. I thus had to use either my Audiophilleo 2 or SOtM USB bridges for an S/PDIF feed. I tried various USB cables to eliminate the chance that the Thrax wasn't copasetic with my split KingRex leash but none worked. The Audiophilleo thus attached directly via its BNC:S/PDIF adaptor, the SOtM ran a Tombo Trøn S/PDIF cable or VdH AES/EBU wire.
with the full Thrax stack and Aries Cerat Stentor speakers
Having done comparisons between eight preamps in the prior Nagra Jazz review which included the Thrax, I cull from that test quietly to present the conclusion pertaining to it in one paragraph. The Dionysos really does behave like an expertly activated passive at all levels, not just above unity gain. The upshot is that if you were to approach a valve preamp for its subtle texturization virtues, the Nagra would be the better choice. Should your idea of truth vs. beauty want to see Salome dance without any of her seven veils—here we'd say that the Nagra leaves the last one in place—the Dionysos goes the full Monty. If we called typical though very finely administered valve textures an infusion of suspended oil in water, the Thrax presents us with water pure. To keep that image accurate, we now must insist not on distilled flat water (that'd be the Tap-X) but on a water rich in natural minerals and perhaps even spiked with very minor carbonation for that added sparkle. Par for this particular course also was a slightly lighter bass balance than the Nagra Jazz which itself was bested by ModWright's truly endowed 6SN7-powered LS-100.

Managing without the common assist of negative feedback or transistor buffers—particularly the first is often not openly credited in product propaganda—the Thrax Dionysos really would seem to fully harvest that old claim of triodes being the most linear of amplification devices ever created. Said claim often rolls up eyes when faced with the majority of non-feedback SETs which don't sound linear by any stretch. But the Dionysos really begs to differ. And there's a proviso. In theory, the fidelity in hifi must be ultimate. More truth should always be better by definition. In practice, how much more we really want could diverge however. In conjunction with my FirstWatt SIT1 monos for example which to my ears are the power amp version of the Dionysos (here the Heros adds at least one of Salome's veils again), I favored the Nagra for its greater succulence and slightly softer handling of transients. To approximate while not meeting that personal benchmark at 10 times the amplifier power, the Thrax threesome came closer than the Jazz + Heros.


In the final analysis the amps proved dominant over the preamps. If we gave out gossamer veils, the Nagra Jazz would get one, the Thrax Heros two. As such the Jazz/SIT1 system was more lucid than the Dionysos/Heros combo. But things got too stark and stripped when the Dionysos replaced the Jazz in the former system. To say it plainly, now truth stole from beauty. The Thrax preamp really should be considered a passive preamp albeit without their usual drive/impedance issues. It's not a nitrous but quicksilver injection. It accelerates and cleans out the cob webs from any dark, slow or veiled system. The only contra indications are setups which already major on speed and extreme transparency. They may not want more of the same but... well, more curves instead.