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

This review first appeared in the January 2011 issue of hi-end hifi magazine High Fidelity of Poland. You can also read this review of the Thrax Dionysos in its original Polish version. We publish its English translation in a mutual syndication arrangement with publisher Wojciech Pacula. As is customary for our own reviews, the writer's signature at review's end shows an e-mail address should you have questions or wish to send feedback. All images contained in this review are the property of High Fidelity or Thrax - Ed.

Reviewer: Wojciech Pacuła
CD player: Ancient Audio Lektor Air 
Phono preamp: RCM Audio Sensor Prelude IC
Cartridges: Air Tight Supreme, Miyajima Laboratory Waza
Preamp: Ayon Audio Polaris III with ReGenerator II power supply
Power amp: Tenor Audio 175S and Soulution 710
Integrated amp: Leben CS300XS custom
Loudspeakers: Harpia Acoustics Dobermann
Headphones: AKG K701, Ultrasone PROLine 2500, Beyerdynamic DT-990 Pro 600 Ω
Interconnects: CD-preamp Acrolink Mexcel 7N-DA6300, preamp-power amp Wireworld Platinum Eclipse, speaker cable Tara Labs Omega Onyx
Power cords: Acrolink Mexcel 7N-PC9300 (all equipment)
Power conditioning: Gigawatt PF-2 Filtering Power Strip
audio stand: Base under all components, Pro Audio Bono under CD
Resonance control: Finite Elemente Ceraball under the CD, turntables change continuously
Review component retail in Poland: €15.000

Preparations for this review took me and Thrax Audio more than half a year. When I spotted their products for the first time at the Munich High End 2010 show, I knew I had to listen to them more closely. They had shown big tube monoblocks with large triodes in the output stage resembling Ayon’s tubes crowning splendidly crafted enclosures. After returning to Warsaw I emailed the Bulgarians asking for review loaners.

Their answer arrived promptly: "Currently we have three products as you can see on our website. In production and on sale at the moment is only the Dionysos preamplifier. The Spartakus monos should be ready in the 3rd quarter of this year and the Orpheus phonostage probably in the 4th.

"Because the development of our products consumes much time, we decided to present pre-production samples to a few people and are now booked solid with orders. Our production capabilities are fairly limited and we would prefer to have our friends listen to the products first because then we will have trustworthy feedback. Taking all of this into account we think we can send you our preamplifier for review by the end of July."

As is usual in such cases, the target date moved by a few months but one fine afternoon the courier brought a nicely looking wooden crate with the preamplifier packed inside. (Actually he didn’t bring it on his own. I first I had to file a complaint because the courier did not want to carry the crate.) This is how all audio products should be packed, not in cardboard boxes which devolve into something not even resembling a box after just one shipment. Everyone needs something far more sensible to really protect their precious cargo. The top of the Thrax crate was adorned by a milled or heat-stamped company logo which I really liked.

The preamplifier itself turned out to be equally interesting. Online pictures don’t present more than a shadow of what the Dionysos really looks like in the flesh. It carries a proud name synonymous with beauty and for once a name doesn’t lie. The unit is sleek and made from thick milled aluminum stock front and back and thick panels elsewhere which merge together without visible fasteners. This is a fully tubed circuit with a 6C4P-EV (6Ц4П-В) rectifier, a SG15P (СГ15П) voltage stabilizer and a solitary twin triode 6N6P (6Н6П) as amplification element where each half powers one channel. Volume control is by transformer with switched secondaries similar to what’s in my Ayon Polaris III. [As owner of Bent Audio’s Tap X, I recognize the volume control and display to suggest that the TVC modules might be the very excellent John Chapman OEM units – Ed].

Unlike my Austrian linestage the Dionysos is very user friendly. Its display shows a numerical output setting for each channel, its i/o ports include balanced XLRs (de/resymmetrized by the transformers as the circuit itself isn’t balanced), a bypass and fixed out (for a subwoofer or headphone amp); there is polarity inversion which may be set/stored discretely for each input and more all stored in a micro processor. And unlike my large two-box affair, the Dionysos is small and in a single chassis. But not everything was peaches. After the first email confirmation I received a note to discuss how to properly match their preamp to a power amp. As it turns out, the Dionysos won’t complement all amps.

Thrax’s boss Rumen Todorov Atarski explained: "Our products are not universal and require some knowledge and experience. For example the amplification factor of the preamplifier is max 20dB (x 10) and available attenuation is 52dB over 24 steps. In combination with a classic 2V-out CD player and classic power amplifier with a rather high  0.5V input sensitivity, usable attenuation will be limited to 10 to 12 steps before things get too loud. Ideally the power amplifier has a far lower input sensitivity like some older 4.5V Krells. This is true also for our own amps. They require 4V to reach full power and present a rather low input impedance. It’s why anaemic preamps based on ICs for example may encounter problems driving them."

These are serious considerations unless one has a variable source like my trusted Ancient Audio Lektor Air whose output voltage I could easily trim to perfectly match the Dionysos particularly since the input sensitivity of my Tenor Audio 175S amplifier was still somewhat higher than ideal (1.3V on XLR, 1.5V on RCA). It’s thus important to acknowledge that the Dionysos has particular requirements and will fare best with power amps of low input sensitivity to fully exploit the low noise floor performance of its circuit.

I used the following discs for this review - Brenda Lee, Let Me Sing, Decca/Universal Music Japan, UCCC-9111, CD; David Sylvian, Secrets of the Beehive, Virgin/EMI Music Japan, VJCP-68879, CD; Jun Fukumachi, Jun Fukumachi At Steinway (Take 2), Lasting Impression Music, LIM DXD 038, silver CD; Tori Amos, Boys For Pele, EastWest/Warner Music, 80696-2, CD; Joe Pass, For Django, Pacific Jazz/EMI Music Japan, TOCJ-90027, HQCD; Tomasz Stańko Quartet, Lontano, ECM Records, ECM 1980, CD; Yoko Ono, Open Your Box, Astralwerks, ASW 88710, CCD;  Brian Eno, Another Green World, Virgin/Toshiba-EMI Limited, VJCP-68658, CD.

For starters, the Bulgarian preamp turned out to be one of the very best of its kind I ever had through my system (and not only my system but for any absolute statements I refer only to my personal reference system in controlled listening conditions). It belonged into the same league as CAT’s SL1 Legend or Ayon Audio’s Polaris III. That already spoke for itself to set the tone.

The actual review sessions took longer than usual because I needed to employ a different methodology than I do with cheaper components or those who more easily reveal their personalities to make pegging their traits easier. For a trio of reviews I did for Audio, I exchanged my usual Polaris III for the Dionysos and over 4 weeks reviewed a lineup of D/A converters (Pro-Ject Box USB, Audinst USB DAC HUD-mx1, Musical Fidelity V-DAC, Arcam rDAC, Cambridge Audio DacMagic, Xindak DAC-5, Stello DA-100 Signature, Music Hall dac25.2, Wavelength Proton, Mytek Digital Stereo96 DA, Cary Audio Xciter DA, Benchmark DAC-1 PR, Naim DAC, CEC DA-1N for their 11/2010 issue); power amplifiers (Balanced Audio Technology VK-255SE, Mark Levinson No.532H, Pass Laboratories XA60.5 for their 12/2010 issue); and integrated amplifiers (Atoll IN400, Luxman L-507u, Mastersound Compact 845, Pathos Acoustics InpolRemix, QUAD II Classic Integrated for their January issue). This was a lot of work but successful. In all these reviews the Dionysos was the reference preamp. It never failed me. Then I listened to it exclusively in place of my Polaris III.