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Headphone amplifier


Manufacturer: HFelektronika
Price (when reviewed): 11 999 PLN

Contact: HFelektronika | ul. Tuwima 2a
42-700 Lubliniec | POLSKA


Provided for test by: 4HiFi


Text: Wojciech Pacuła
Images: Jacek Grodecki | Wojciech Pacuła
Translation: Marek Dyba

No 197

October 1, 2020


Feliks-Audio is a Polish family company from Lubliniec, specializing in the production of tube amplifiers. It is known primarily for its superb headphone amplifiers. For the review we received the latest version of their flagship model, Euforia 20th Anniversary Edition. As the name suggests, it is one of models developed to celebrate company's 20th anniversary.

t was only recently that I had an opportunity to review another product, which was introduced to the market by the end of last year as part of the celebration of the 20th anniversary of the Feliks-Audio company, i.e. an amplifier based on my favorite 300B tube - Arioso 300B 20th Anniversary Edition (see HERE). I started that text by wondering how was it even possible that I, a big fan of tube devices, a man born and raised in Gliwice (the distance between Gliwice and Lubliniec is less than 50 km) had never tested any of the Feliks-Audio devices before .

I didn’t know the answer then and I still don't. But richer with the experience of this first review, I am even more surprised. The Arioso 300B, which has already permanently replaced in the brand’s lineup the previously offered amplifier of the same name, but based on 2A3 triodes, turned out to be an excellent product confirming that the grass is not always greener on the other side of the fance, as they say. For this particular type of amplifier, the Arioso 300B is relatively inexpensive, and yet in terms of sound quality it can easily compete even with much more expensive competitors from well-known brands. And it looks great in the room, despite the fact that this effect was achieved with relatively simple means.

| Feliks-Audio

The Feliks-Audio company is a result of the passion of the senior member of the family, Mr. Henryk Feliks, an electronics engineer who, like many famous audio designers, combined his knowledge of electronics with a love of music, initially building devices for his own use, then for friends and even local music bands. Ultimately, in the late 1990s, he decided to start manufacturing tube amplifiers full-time, establishing the Feliks-Audio brand.

Its first successful product was the Espressivo headphone amplifier, which is still offered today in the Mk2 version. And it is the headphone amplifiers that are still the very core of this Polish brand's lineup, but it is not the only type of devices offered by the company. There are also several „classic” amplifiers for loudspeaker systems, including the Dual monoblocks based on 2A3 tubes, or the aforementioned Arioso 300B.

In 2014 three sons, Łukasz, Piotr and Michał joined Mr. Henryk, taking over a number of tasks related to the company's operations. This, in turn, allowed the senior of the family to focus on what he likes most - developing new and improving existing products. Including the anniversary versions of several of them, which turned out to be so successful that they were added the regular lineup (one of the is the Arioso 300B, the other is the reviewed version of the Euforia).

Over the years, the company has gained recognition of customers in many countries around the world. Today it has distributors in over twenty countries, with the newest partner being a company from exotic India. It seems to me that Feliks-Audio brand is better known and appreciated abroad than here our market, although this weird situation is slowly changing, or should I say improving. In an interview I conducted with him while reviewing the Arioso 300B Łukasz Feliks mentioned that their top model of the headphone amplifier, Euforia, was even used as a reference by Focal (more HERE), which may be known primarily as a loudspeaker manufacturer, but also offers high end headphones.

| Euforia 20th Anniversary Edition

For this review for the "Polish" issue of "High Fidelity" we received a special, jubilee version of the current top model Euforia, which introduced a number of changes compared to the 2018 version. The latter you may remember from Wojtek’s review (see HERE), who seemed to like it a lot. I will discuss differences between these two versions in a moment, but first let me tease you with an information Mr. Łukasz shared in the above mentioned interview. If all goes well, beginning next year Feliks-Audio plans to premiere a new flagship headphone amplifier. It will be a design with a balanced input and output, featuring a "high power tube". The company is also planning to move to new headquarters as the current one has gotten too small.

Probably not all of our readers have come across Euforia before, so let me start with some general information and then move on to the differences between the versions. The flagship headphone amplifier from Feliks-Audio is a tube device with a stabilized solid-state power supply. The manufacturer uses the excellent Psvane CV181-TII driver tubes, i.e. 6SN7 replacement, and 6AS7G power tubes. In both cases, the owner of this amplifier has a lot of options to modify amplifier’s sound by so-called tube rolling. There are many substitutes on the market, including the NOS type tube and each of them will have some impact on the Euforia’s performance. The former (Psvane) can be used interchangeably with: 6N8S, ECC32, 5692 or 6F8G, and instead of standard power tubes, one can use: 6080, 5998, 6N5P, 6N5S, ECC230, 7236, or CV2523.

Importantly, Mr. Henryk decided to use a topology called OTL (output transformer-less) - the name is self-explanatory - there are no output transformers. This is a perfect solution, especially for medium and high impedance headphones, but as the listening session with Sonorus VI headphones from the Japanese company Final Audio proved, low impedance models also sound excellent with the Euforia AE. The user has at his disposal one unbalanced input (RCA), one adjustable unbalanced output (RCA), which combined with volume control adds another function to this device - it can act as a preamplifier, and a headphone output for a large jack (TRS 6.2 mm) located on the front panel next to the volume knob.

You will find the model’s name and a power LED on the front panel below the headphone output. On the centrally placed volume control knob’s perimeter there is a volume scale marked with white dashes, and there is also a marker on the knob itself, which allows you to see its current position even from a few meters away. In the lower right corner there is a company logo with an inscription above it indicating that this is the special anniversary edition. On the back panel, next to the main switch, there is also a second one, which turns on the CrossFeed function, which Wojtek described in detail in his review so let me refer you to it. The whole device sits on characteristic white, angular anti-vibration feet, which do a good job both in terms of isolating the amplifier from vibrations and as a visual element contrasting with the color of the entire chassis.

The device is small, neat, well-made and finished. To distinguish it from the "regular" version, manufacturer used a high-gloss premium “space gray" finish. Five layers of varnish are applied using a technology derived from automotive industry. It looks great also because the reflections of the amplifier's surroundings are visible in the mirror surfaces. The aesthetic design definitely attracts the eye but also dust so be prepared to spend some time wiping it off with a soft cloth. Well, there is no rose without a thorn, as they say.

We can see the other changes compared to previous version by peaking under the hood. You will find there a different, excellent low-noise, shielded transformer, high-class capacitors (ClarityCap), resistors and new, improved current sources. As if that were not enough, instead of pure silver wires, this time all the internal cables were hand-made in house using a monocrystalline copper UPOCC copper from the Taiwanese company Neotech.

In a word, despite the apparent similarities, there are actually quite significant differences compared to previous version and they undoubtedly have a big impact on the performance.


Recording used during review | a selection | While listening to the Euforia 20th Anniversary Edition, I used three sources. My "custom" PC worked on the digital front, sending the signal via the David Laboga Custom Audio USB cable to the USB signal regenerator, Ideon Audio 3R Master Time and using another Laboga USB cable to - alternately - the LampizatOr Pacific D/A converter and Weiss DAC501, which were connected to the Euforia input with a Hijiri Kiwami interconnect.

The analog source was my J. Sikora Standard Max turntable with the tonearm of the same brand, the KV12 armed with the Air Tight PC-3 cartridge, sending a signal to the Thoeress Phono Enhancer phonostage and then with the Hijiri HCI-20 IC to the Euforia input. During the test I used two of my favorite headphones - Final Audio Sonorus VI and the planar Audeze LCD-3. The amplifier was tested with a standard set of tubes supplied by the distributor.

Recordings used for the test (a selection):

Natural jazz recordings, fonejazz, DSD64
⸤ AC/DC, Back in black, SONY B000089RV6, CD/FLAC
⸤ Alan Silvestri, Predator, Intrada MAF 7118, CD/FLAC
⸤ Arne Domnerus, Antiphone blues, Proprius PRCD 7744, CD/FLAC
⸤ Georges Bizet, Carmen, RCA Red Seal SPA 25 064-R/1-3, LP
⸤ Hugh Masekele, Time, Sony Jazz 508295 2, CD/FLAC
⸤ Isao Suzuki, Blow up, Three Blind Mice B000682FAE, CD/FLAC
⸤ Mccoy Tyner, Solo: Live from San Francisco, Half Note Records B002F3BPSQ, CD/FLAC
⸤ Michael Jackson, Dangerous, Epic/Legacy XSON90686F96, FLAC 24/96
⸤ Michał Wróblewski Trio, City album, Ellite Records, CD/FLAC
⸤ Mozart, Cosi Fan Tutte, dyr. Teodor Currentzis, wyk. MusicAeterna Orchestra, Sony Classical B00O1AZGD6, LP
⸤ Możdżer Danielsson Fresco, The Time, Outside Music OM LP 002, LP
⸤ Rachmaninow, Symphonic dances, Etudes-tableaux, Reference Recordings HRx, WAV 24/176
⸤ Renaud Garcia-Fons, Oriental bass, Enja B000005CD8, CD/FLAC
⸤ Rodrigo y Gabriela, 11:11, EMI Music Poland 5651702, CD/FLAC
⸤ The Ray Brown Trio, Summer Wind, Concord Jazz CCD-4426, CD/FLAC

I HAVE TO ADMIT, that I have not listened to much music through headphones for quite a long time, maybe except in-ear headphones combined with some portable players during the holidays. Why not? Firstly, I always preferred to listen to the music using loudspeakers, secondly, it's been a while since my last headphone amplifier test.

And finally, last but not least, I don't even currently have my own high-end headphone amplifier. The test of the Weiss DAC501 D/A converter, which features a very good headphone output, reminded me, however, that it is also a valuable way of communing with music.

So I was waiting for a chance to review Euforia AE with curiosity, not only because of the name suggesting a unique experience, but also because I had heard and read only highly positive opinions and reviews from all over the world about previous versions of this device. It so happened that just before I started to assess the Feliks-Audio, I tested the latest, smallest SPEC integrated, the RSA-777 EX, which also features a really good headphone output/amplifier, but with a small jack output. So I finished that test by assessing its capabilities using the Sonorus VI Final, equipped as a standard with a cable terminated with such a plug (and the performance was really good, by the way).

Immediately after that, but using a large jack adapter, I connected the Sonorus VI to the output of the Euforia 20th Anniversary Edition (I will use AE). And...? I quickly realized that while the SPEC’s output is really very good - for an integrated amplifier designed for loudspeakers additionally featuring a headphone amp one could even say: excellent. But the Euforia AE comes from a different league. Sure, I could have predicted it - after all, it is a dedicated flagship "headphone" from a renown manufacturer, but nevertheless the scale of the differences was surprising.

It took me literally 15 seconds (I turned on the amplifier an hour earlier, so it would warm up properly) to realize it. Final headphones offer a full, saturated sound, and with the SPEC amplifier, which by the way sounds a bit "thinner" than the more expensive models of this manufacturer, they didn’t quite show it. In any case, switching to the Polish amplifier reminded me quickly how much these, after all, not so expensive headphones, really have to offer.

Lang Lang's classic piano sounded strong, deep and very sonorous, just like Jessica Williams' jazz one. Where previously (with SPEC) more emphasis was placed on hammers hitting vibrating strings, now both pianos had more body, so to speak, which happened also with Ron Carter's double bass. Listening to the latter I also heard that Euforia AE changed the proportions between the strings and the wooden body, but it was now that they actually became right.

Importantly, the tested amplifier does not have any problems with the transients - these are fast and strong, so each hammer hitting the string or finger plucking bass string had the right immediacy and power. Then it quickly moves the sustain phase and finally to a long, full decay. I am very sensitive to the latter, so while listening to Euforia AE, I enjoyed the long lasting notes a lot.

The Euforia AE presented an excellent differentiation in terms of both, timbre and dynamics. The former helped me to hear how colorful, tuneful instrument the double bass is, how great scale of sounds it is able to reproduce in the hands of fantastic, talented bassists, such as the aforementioned Ron Carter, but also Ray Brown, Stanley Clarke, Christian McBride, Marcin Oleś and others. Especially the later listening session with Audeze showed how deep down the Feliks-Audio amplifier can go, how beautifully it is able to saturate even the lowest sounds with explosive energy. The outstanding dynamics, both in the micro and macro scale, allowed all these brilliant musicians (and many others) to truly shine, to perform at their best.

I also enjoyed Rodrigo y Gabriela albums a lot. Their explosive style of playing acoustic guitars, rooted in heavy metal, was presented by Euforia AE in a wonderfully lively, fast, energizing way, which reminded me of the way GrandiNote MACH4 speakers sound like. With the Sonorus VI headphones, the sound, although bursting with energy, was shown in a clean, transparent way allowing me to effortlessly focus on performer of my choice. It was amazing to hear a combination of such a high dynamics of the presentation with its full control and the so-called flow, bringing it even closer to live music.

One of the first songs I listened to after switching to my personal top favorite Audeze LCD-3, was the Frankie Goes to Hollywood’s Welcome to the pleasure dome in the longest (I believe) version (lasting well over 13 minutes). From the very first moment I literally froze in my chair - I was surrounded by the jungle and its sounds. When the music finally came in, I turned up the volume a bit and after a while I let myself be carried away by the rhythm and unusual atmosphere of this piece.

It’s a track from my youth, as I discovered it several dozen (34!!!) years ago on the Radio Three's Hits List, so I’ve listened to it many, many times, but never in the way Euforia AE presented it for me. The reviewed amplifier recreated the climate and ambiance of this song in a way that was impossible to resist. The sounds of the jungle, vocals, acoustic guitar, strong basses, drums or synthesizers sounded equally well, delighting with the richness of sounds presented in an orderly, smooth, coherent and spatial way. It's quite a complex piece, but the Polish amplifier handled it simply effortlessly, and the final Welcome sent shivers down my spine. And then play it again and continued with the whole album :)

Although a tube amplifier does not seem to be an obvious choice for this type of music, I spent a lot of time listening to rock and hard rock recordings. They proved that Euforia AE is a great partner for such music. Why? Because, like any good tube device, it has an exceptional midrange to offer - colorful, dense, strong, but also resolving, clean, rich in details and subtleties. And if you think about it, rock music is largely based on electric guitars, or ... mostly mid-tones.

The Feliks-Audio amplifier, depending on the headphones, either (with Audeze) made the guitars “fleshy” as rarely ever, or (with Final) made them sound clean, a bit harsher, and sometimes even sharp. In recordings of a slightly worse quality, the former version was preferred, but I must admit that when listening to the slightly higher quality ones, I preferred the combination with Japanese headphones, which resulted in more „fire” in the music. Neither one nor the other headphones driven by the Euforia AE allowed the recordings (in these genre usually not of the highest/audiophile quality) to sound too sharp or shrill. Theoretically, this means a certain departure from absolute fidelity to recordings, but in my opinion it is fully justified and even desirable, because it allows you to focus on music and have great fun with it even if it is not perfectly recorded and/or released.

Last but not least I used the Euforia AE as a preamplifier in a system with the already mentioned Feliks-Audio Dual monoblocks (on double 2A3 tubes) driving my GrandiNote MACH4 speakers. The change of a role in a system did not result in an appearance of any completely new set of features of the tested device. As a line preamplifier, the Euforia AE continued to impress me with powerful, dense, full-bodied sound and an indication of its truly high class class, namely a combination of these qualities with high resolution, clarity and spaciousness, with a great dynamics added on top.

Comparing it to my Audia Flight FLS1 solid state preamplifier, which is twice as expensive, the differences were clearly audible. The Italian device, also offering smooth, rich, dynamic sound, shifts the accents towards neutrality and precision. The Euforia AE focuses more on the naturalness of the sound, timbre fidelity, saturation of the sound, emotions, spatial aspects, and the palpability of the performers. It shows the events on stage a little closer to the listener, but without pushing them forward. At the same time, it builds a deep, but also sound-dense scene. This is an open and dense sound at the same time - a beautiful, amazingly musical combination.

| Summary

I started this text by stating that I have rarely listened to music through headphones for quite some time. After listening to the Euforia 20th Anniversary Edition, it became clear to me that the only reason was the lack of a high class amplifier, such as the new Feliks-Audio product. It is not a typical "tube-sounding" device. Sure, it delivers a slightly warm, dense, saturated, incredibly smooth performance, but at the same time it delights with sound’s purity and dynamics. It offers a uniquely spacial presentation, but one combined with precision. It can play fast, strong, but also in a particularly immersive way when it comes to sophisticated recordings of small ensembles, jazz or vocals. It is one of the best headphone amplifiers I had a chance to listen to! That’s how a true high-end sounds like.

The device is small, neat, well-made and well-finished, offering users plenty of options for tube rolling, which in turn allows them to tune the sound. And finally, if you buy the Euforia AE and the appropriate power amplifier/s, such as the proprietary Dual model, you will have an extremely universal, complete high-class amplification system. All you need to do is to add a high quality source/s, appropriate headphones and loudspeakers and you can focus entirely on what is most important in this hobby, i.e. music.

Regardless of whether the Euforia AE will be used as a headphone amplifier or as a line preamp or both, you can always count on a unique, high satisfying musical experience with it.

Technical specifications (according to the Manufacturer)

Input impedance: 100 kΩ
Frequency range: 7 Hz – 80 kHz (+/- 3 dB, 300 Ω)
Output: 280 mW
Gain: 20 dB
THD: 0.4% (300 Ω, 20 mW)
Optimal headphones impedance: 32-600 Ω (incl. Planar-magnetic ones)
Headphone output: TRS 6.3 mm
Dimensions (excl. Tubes): 295 x 203 x 165 mm
Weight: 7 kg