Mono & Stereo Review

Thrax Audio Heros review preview

I’m more than thrilled with what we could set down as a power amplifier mecca test of comparing the illuminating Thrax Audio Heros and Teres power amplifiers. As a top of the cherry, the Spartacus monoblocks will join in at a bit later date to conclude the complete exploration of the current production of the Thrax power amplifier line.
As you can read more in-depth below all new Thrax products are born as a completely different approach to the ultra-high-end reproduction of the sound. So these power amps do actually not compete with each other but offer a variety of choices suited to different system setups. And before you ask why Thrax is offering such an array of amplifiers the answer is very simple.  Because they can! Intriguingly inspiring…
Heroes’ monoblocks represent the company’s finer exploration of Class A Hybrid tube fet technology. They offer 100 watts of Class A via a unique hybrid transformer-loaded amplifier design that embraces the renowned concepts with contemporary high tech. You won’t see output transformers in typical Class A amplifiers and still, you’ll find them in Heros. It’s not a non-working concept, but following this route cost a money. I love the logic behind such a concept and the difference is as factual as it gets. But more about this latter.
Teres on the other hand is a transformer-coupled hybrid power amplifier based on classic tube amplifier topology. The single-ended tube input stage is loaded with a phase splitting transformer, which controls two separate single-ended amplifiers out of phase for output. Teres implements audiophile super long life C3g input tube, silicon carbide rectifiers, shunt regulated power supply, solar cell bias of output stage, battery bias of input stage, and microprocessor-controlled operation. They have no feedback, uses a special grade screened power transformer as well as JFET/MOSFET cascode output devices. Now if that’s not enough to get you interested, then recheck of many priorities is mandatory.
In my preview of the Thrax Audio Orpheus phono preamplifier here: link I already gave a great overview and insights of this Bulgarian High-End audio manufacturer. Anyhow… To wrap it up shortly. These days you rarely encounter such a proficient, self-sufficient, and highly resolved manufacturing premises. And one needs to understand the Thrax Audio for what it really is to appreciate it on the level it deserves.
Driven by Rumen Artarski’s unlimited passion for the highest possible musical reproduction Thrax Audio unique venture is more of the extreme, ultra-high-end audio design laboratory than your typical high-end audio manufacturer.
A few months ago at my company/factory visit, I’ve had a chance to see and understand the inner workings of Thrax as a company. It was an eye and mind-opening experience that led me to respect it even more.
Anyone knowing Rumen feels similar about him. He’s one of the rare connoisseurs and high-end audio aficionados. A broadminded and culturally embossed person with an exquisite taste and knowledge that surpasses your typical expectations.
Thrax Audio spirit for me reflects the traditional Japanese approach to the production process where the creational phase is as important as the end result. One must really see the Rumen collection of rare tubes, exotic output transformers, chokes, etc. to fully understand the dedication and unabridged enthusiasm. There is simply no other company doing things the way Thrax Audio operates. This is also due to Mr. Artarski being a successful business carrier, which created immense safe grounds for the in-depth R & D of the Thrax Audio product. They can have a completely different time frame and research complexity than most of the gear out there. As a company, they are not hard to press from the very first moment that new product development starts. No typical taximeter ticking clock is needed. This leads to a completely different set of products that can operate on very different and proficient levels.

We discussed many things with Rumen, past and present at my visit and over our correspondence. I wanted to understand his mindset and why he’s pursuing his venture the way he does. I’m no rookie when it comes to the history of high-end, basic designs, different topologies, etc. But during our conversations, I’ve found myself hitting the conversation stop button too often! Yes, he’s done his homework overtime and overloaded.

Seeing the literature, prototypes, schematics, and amount of contemplating behind the products left a lasting impression on me. It still resonates and it’s a great reminder whenever I’m starting to contemplate about the actual meaning of high-end audio. Being inspired, my reading was revived with much more complex material.


These days I’m not lightly inspired or awaked out by the equality of all the gear coming in and out. That’s why many times I don’t even explore further if a certain criteria is not met. Regardless of the price.
There are so many mediocre high-end audio products eschewing the chewed circuits and designs, that it’s not even funny anymore. Call it a matter of globalization and greed in simplified reasoning. A clear indication of the non-strange logical conclusion of why most of the sound results of amplifiers are bland and boring! Its also a matter of the goals wanted to be met. For most companies, the main ruler is a quick turnover and cashing in. Whit this kind of modus operandi what can be expected as the end result? Saving on everything and calculating to the last bit leads to the employment of electronic engineers knowing little or nothing of the high-end and ultra high-end audio industry mechanics. The initial job of proper design and “voicing” in most cases actually never happens.
There is a huge difference between designing a typical amplifier and a high-end audio counterpart. Many tried to cross the bridge from the other side, but few of them succeeded. Thrax Audio employs people with specific high-end audio skills and with decades of particular experiences. Sometimes, if needed they would bring in the top most specialists, even if only for the specific project being developed.
And the difference between typical and ultra high-end audio potently designed power amplifier? Night and day! Not even a debate is needed when comparing the sound of such two side by side.
This is why I’m pushing the agenda of intelligent research and making the proper homework for people who are in the process of upgrading the system and changing or purchasing new high-end audio components. I do believe in common sense and the intelligible nature of people willing to shelve out such a hefty amount of money.


Bauhaus, art deco, with unprecedented elegant simplicity, that cuts with the contemporary aura and fails to be ostentatious like most of the high-end audio gear at any point. Elegant and timeless. Love it!


Thrax Audio Hero power amplifiers have shown their DNA and recognized sound orientation from the first few notes being played. They carry the familiar “voicing” I’m used to from the Dionysos and Orpheus. Continuity is not easily achievable. Especially with building different components, one wants to open new, uncharted territories, yet without losing the most important orientation. And for Thrax, this is clearly the sound of real music.
There are many critical points that embark a level of needed attributes to let any product reside on the plane of the high-end audio. What to talk about the ultra-high-end, even more, niche market. Thrax Heros sits both firmly and boldly on their designated throne without even blinking…


Leonard Cohen’s last two albums represent some of his finest music up to date. They are both very well recorded and can easily reveal whats is possible within any system. Call it simple pop or whatever you want it. To really sing these songs needs more than properly designed electronics. The same demand goes for Lokua Kanza’s latest album Nkolo. Pure impact of the African lyrical compositions. Simplistic yet complex at the same time. To get into the core of the songs like Elanga Yu Muinda is no easy task. Here even a few of the best-specced amps fall short of the vibrancy needed to encompass Lokua soulful composing.
Grieg Unheard Reza e iRagazzi fantastic album is another album encompassing majestic execution that really needs a profound amplifier in order to come alive and Janos Starker protégée Maria Kliegel endearing playing falls even more so in the line of the proficient demands and sound attributes.
Thrax Hero mono blocks step further into the rendition of these albums and artists with an unfettered hologram-like three-dimensionality. They could render the music under the scope precisely and with the omnipotent dynamic barrage which can minutely shift from pianissimo to forte fortissimo without a sweat and without losing a pace. Even most importantly the essence of music is touched and revived withe Heros.


Heroes possess an intricate translucent nature that reveals music for what it is. The most potent medium of profound interaction between performer and listener. Heroes, rich in tonality, zesty and radiant are capable of harmonically contoured reproduction that is both elusive, lyrically and most important sound- wise reiterated at each play.
Thrax team shows profound dexterity and they are stalwart to the Rumen Artarski strong determination regarding how Thrax products should sound like.
The unrestrained, enchanted music flow is most inspiring. Heroes hybrid concept brings the most inspiring level of transparency, details, and constitutional points of upper echelon league of the performance. For any Class A amplifier, this is quite an achievement.
I’ll continue when a pair of Teres mono blocks will hit the shores of Mono & Stereo HQ’s. My venture came to the point where I can be very selective in my choices of the products being reviewed and tested. In this way, more focus and listening can be dedicated to stand-out equipment. Thrax Heros certainly represent a healthy new breeze of the products being more than worthy of highlighting.
Stay tuned….
Matej Isak

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