pl | en

Headphone amplifier

Fezz Audio

Manufacturer: FEZZ AUDIO
Price (when reviewed): 3490 PLN

Fezz Audio
ul. Mazowiecka 20
16-001 Księżyno | Polska

Provided for test by: FEZZ AUDIO

t was hard for me to believe it - when I was preparing the materials for this test, I searched for the Fezz Audio amplifier tests I carried out. It turned out that there were just two of them, of the Silver Luna and Titania. And yet it seemed to me that I know the sound of Fezz Audio really well, I have it in my head and ears. And I do, I really know how the Fezz Audio amplifiers sound like, because I spent the whole last year traveling around Poland with workshops, during which we conducted half of the listening sessions using the Titania model (more HERE).

So when in June last year one of the owners of this company, Maciek Lachowski, called me and said he was thinking about the project of a new amplifier, I thought it was about expanding the offer with an even more expensive model - after all that's where real money comes from. I was wrong, and Maciek turned out to be a real dreamer who wants to share his success with others.

What is it about? As you could have seen during the last year's Audio Video Show, the company's portfolio expanded, but from below. An affordable, nice, robust, well-thought-out amplifier called Lupi (from Latin lupi - wolf) was prepared, using interesting and rarely used PCL86 tubes (triode-pentode). The price was set at PLN 3490 and I really do not know how the company wants to earn on it. Perhaps the key is that the most expensive elements of a tube amplifier, meaning transformers, are produced by its separated branch called I do not see any other explanation.

| α Lupi

Already during that conversation, Maciek told me that he would like Lupi to appeal to younger music fans and freaks, for whom the electron tube is an important symbol. In addition to the low price, it had to be as versatile as possible, and one of the most important functionalities of modern sound sources, both D/A converters and amplifiers, is the presence of a headphone output.

I thought then that it was a great idea, a very natural one. However, it turned out to be impossible to implement. For the amplifier to be made at a quality level for the people in Fezz Audio to accept its sonic performance, its price would have to be higher than expected. Maciek, regretfully had to shelf the project, opting for a classic integrated amplifier.

And he was right. As the exhibition in Korea and the first orders resulting from it proved, the amplifier was accepted as it was. Already then it was called α Lupi (alpha). The solution for the situation was to create a complementing device, and amplifier designed only for headphones, model Ω Lupi (omega).

| Ω Lupi

The genesis of this model is connected with the research that was carried out on the prototype of the original Lupi, still with the headphone output. It turned out that this particular system, these specific tubes cooperating with toroidal output transformers, are ideal for powering headphones. So the idea was dusted off and in this way the amplifier being the protagonist of this test was created.

On the outside, both amplifiers - Alpha and Omega - are almost identical. These are simple, tasteful forms in burgundy and black, with aluminum touches of manipulators and logos and white typography. The front is painted with high gloss finish and the other walls are powder-coated. In turn, the transformers covers are black. The device features two knobs - volume control and output impedance control, so you can adjust it to the headphones you use. There are three positions to choose from: "Low", "Mid" and "High".

The circuit is based on a push-pull topology, but there are only four tubes - why? Maciek reached for a very popular, and therefore inexpensive, cool PCL86 tube. There are two tubes in one glass - a triode and a pentode, and this model was used in television sets. Its version called ECL86, of lower voltage, was in turn found in the Polish amplifiers of Fonica and Unitra. Suffice to say, my first tube amplifier I made using power amps from a turntable with an amplifier called Stereo 240, and the preamplifier I based on the ECC83 tube, using the simple layout included in the book An Audio Approach To Audio Frequency Amplifier Design, published by The General Electric Co. Ltd. of England from 1957.

The Fezz Audio amplifier features a shorter because amplifying path because one of the triodes in PCL86 is used for phase reversal and the other is a driver - the potentiometer is placed in front of the circuit. Let us add that the tubes used here were produced in a Polish factory Polamp. It is a pity that the Russians and Czechs were able to use the machines and skills of people and their tubes are known all over the world today, and Polish ones are lost in history ... But that's life - it's great that someone reminded us of them and in such an interesting amplifier.

Owner, designer

Omega Lupi, is the design that we worked on the longest in our history. We opened the project in March 2017 and presented the prototype in November of the same year during the Audio Video Show in Warsaw. We wanted the opinions of the users and even though they were positive, I knew then that the design would satisfy me only when Omega Lupi is able to drive even the most demanding headphones - also those with extremely high impedance.

I thought there were a lot of headphone amplifiers on the market, but either they were simple designs for relatively cheap headphones, or very expensive ones, for extremely demanding customers, and I wanted to create a universal headphone amplifier for a wider group of people listening to music in this way.

That is why, right after the Show ended, we started work from the very beginning. The chassis was the only element left from the prototype. Everything inside was rebuilt from scratch. As you well know, the heart of each tube amplifier are not only the tubes but, above all, transformers, and we spent the most time building those. But it's probably obvious - is a strong player on the market of audio transformers and we have unique experience with different types of designs.

Omega Lupi is a one-of-a-kind amplifier. Most of the headphone amplifiers are OTLs - that is, featuring no output transformers. And I wanted the headphones to be treated in our design as a loudspeaker set, because what other than good loudspeakers headphones are? The only way to achieve this is to match their impedance using transformers - in other words, do it in the same way as in an integrated stereo tube amplifier.

We have therefore designed winding in our transformers to optimally match headphones with low (up to 32 Ω), medium (up to 300 Ω) and high (up to 600 Ω) impedance. Thanks to this solution we have achieved optimal working conditions of headphone drivers, and thus negligible low distortion and great dynamics while maintaining the tube character of the sound.

Omega Lupi is a very efficient amplifier. During the designing process, we examined about 30 pairs of headphones - starting from the simplest dynamic ones, through several hundredth ohm ones used often in studios, and ending with planar Audeze models. Each and every time our amplifier had enough “juice” to properly drive every cans.

At this point, an important question comes to mind: why PCL86? One of the reasons is historical - we built our first tube amplifier called Laura (still as using this tube, which captivated many listeners. The second reason is personal - I value this tube very much. Considering its price, availability, sound and origin (POLAMP Nakło), we could not deny ourselves the pleasure of designing an amplifier using the PCL86 valve.

This is an outstandingly engineered design, technologically advanced (two tubes in one glass enclosure) triode-pentode. It's a pity that nobody is producing them today. Fortunately, due to the wide availability of NOS tubes (these were, after all, very popular TV tubes), they are easy to buy and at very low prices. Fezz Audio bases on the NOS tubes made by the Polish company Polamp, which are still available on the market and I believe that someday they will come back to the market.

I would like to draw your attention to the restrictive selection of tubes and the exceptional care of assembly. It is about exceptionally demanding sound aspects - after all, according to the design assumptions, it is an over-ear speaker system. So we put the ear in the speakers and there must be an absolute silence, black background, no hum - just silence.

The Fezz Audio Ω Lupi amplifier was tested in the "High Fidelity" reference system and compared to the Ayon Audio HA-3 amplifier. The signal was sent to it from the Ayon Audio CD-35 HF SACD player with the Acute Revive RCA-1.0 Absolute-FM and Crystal Cable Absolute Dream interconnects. It was powered by the Acoustic Revive Power Reference Triple-C cable.

The listening was mainly performed with planar headphones HiFiMAN HE-1000 V2 (nominal impedance: 35 Ω | sensitivity: 93 dB), in the "Mid" position of the impedance switch. Which is interesting, because the nominal impedance of this model would suggest switching to the "Low" position. So one should try out all three positions every time and choose the best for particular headphones. Additional listening was performed with planar headphones HiFiMAN HE-6 (impedance: 38 Ω | sensitivity: 89 dB), the dynamic Sennheiser HD800 (impedance: 300 Ω | sensitivity: 102 dB) and Beyerdynamic DT-990 Pro (impedance: 600 Ω | sensitivity: 97 dB).

FEZZ AUDIO in „High Fidelity”
  • TEST: Fezz Audio TITANIA | integrated amplifier |
  • TEST: Fezz Audio SILVER LUNA | integrated amplifier | RED Fingerprint

  • Recordings used for the test (a selec- tion)

    • Puer natus est, Stile Antico, Harmonia Mundi USA HMU 807817, SACD/CD (2010)
    • Aretha Franklin, A Rose Is Still A Rose, Arista Records 18987-2, Master CD-R (1998)
    • Depeche Mode, Construction Time Again, Mute Records Ltd/Sire/Reprise IMS/2007, Promo CD-R + DVD-R (2007)
    • Depeche Mode, World in my eyes/Happiest girl/Sea of sin, Mute/Sire/Reprise 21735, maxi-single (1990)
    • Electric Light Orchestra, Out of the Blue, Epic/Sony Music Japan SICP-30111, 2 x Blu-spec CD2 (1972/2013)
    • Giulio Caccini, Dolcissimo Sospiro, wyk. Roberta Invernizzi, Divox CDX-70202-6, SACD/CD (2008)
    • Glenn Gould, Bach: The Goldberg Variations, Sony BMG Music/Sony Classical/Zenph Studios 9703350-2, “Zenph Re-Performance”, SACD/CD (2007).
    • Tsuyoshi Yamamoto Trio, Misty, Three Blind Mice/First Impression Music FIM SACD 062 SACD/HDCD (1974/2004)

    Japanese issues available at

    The sound qualities of each audio product, and thus the amplifier, can be assessed from two points of view - as a representative of a specific price category and in absolute terms. Fezz Audio Omega Lupi kills in both. This device looks and sounds like amplifiers for 5000-6000 PLN and more. Although it is not a perfect amplifier, it does not even aspire to this role, it has everything it needs to become the basis of any, really any headphone-based system.

    Its sound is modeled - modeled so, that it is deep and saturated and that the bass is an important component of the creation, not just an ersatz of low frequencies, as is usually the case with headphone amplifiers. Modeling goes here in the direction of smoothing the top and shifting the center of gravity, focusing our attention on the lower midrange. It gives us what we call "groove" or "stepping bass".

    I do not know whether it was the Fezz Audio designer's intention, and how much was it their intuition, something like an internal "voice", the sound engineers from the 1950s followed while creating perfect jazz recordings, that until this day remain an unattainable model, who were listening to the recordings they were preparing using small speakers with high distortion showing a fraction of what even cheap speakers offer today.

    Depeche Mode fans - attention: this is an amplifier that could be "dedicated" to this music. It absolutely does not close it for other types of music, I will come back to that later, but once you hear Shame from a tonally challenging album Construction Time Again, or spend a moment with Happiest Girl from the mix released on World In My Eyes / Happiest Girl / Sea of Sin maxi-single, you will know that this amplifier will allow you to truly enjoy your favorite band.

    The thing is that the Fezz Audio amplifier shows the colors as if it was natural, that the CDs have their own life, as if it was normal that it is a creation, whose spirit, design, or whatever we call it, should be brought out. And, as Mr. Okihiko Sugano, the owner of Audio Lab Record once said, there are musical instruments used, which in this case happen to be audio components. Omega Lupi delivers a deep sound, controlling the events, as if the membrane of headphones did not weigh anything and at the same time weighed a ton - the former because the sound is so fast and the latter because the bass has weight and slam.

    I'm talking about the problematic Construction Time Again because it's an album recorded after a phenomenal, analog recording Abroken Frame using samples, various strange sounds, and therefore quite hard, often even tiring. The tested amplifier showed this aspect, did not try to hide it. But on the other hand, it filled it up enough, it made sure nothing disturbed me, I could hear chords, density, layers. In turn, the aforementioned single comes from the Violator, which was mastered on ½ "analogue tape, which makes it sound fantastic. And it was with this album that it became clear that in absolute terms the device emphasizes the mid-bass, it gives it a lot of power and is not strictly controlling it at the bottom.

    In both cases the headphone amplifier delivered something that in many headphone systems is almost non-existing - with the right headphones it is able to create a huge space. I am thinking about recordings from the opposite musical spectrum, for example about Dolcissimo Sospiro released by Divox Antiqua, or madrigals and arias by Giulio Caccini (XVI-XVII century) performed by Roberta Invernizzi. The presentation was beautifully arranged tonally in a space of a large interior. I could clearly hear the foreground, which was not placed inside my head, but a bit ahead of me, but also fantastic reverbs and reflections.

    I've mentioned these two types of music not out of spite and not for show, but to say something else: it is a very universal device. Its tone is quite dark, at least in comparison with semiconductor amplifiers, but it is darkness full of meanings if you can say that. The cymbals sound vibrant and are built up and down, and if the recording was made in analog domain and without a noise reduction system - let it be Misty by Tsuyoshi Yamamoto Trio - we will know it immediately, without the need to listen to and split the hair in four. But we will always know that it is not the treble that is most important here.

    This device communicates with listener directly. It's just that it does not close us in the sounds close to us, even though it's the easiest way to achieve such effect of "closeness". As I said, the sound of Omega Lupi is incredibly "wide", it has momentum. One would therefore assume that it would be presented form a distance. But it is not. It is direct, and this immediacy results from the outstanding speed with which the sound is reproduced and from its density, which is delivered to us immediately, coherently.

    HiFiMAN HE-6 | Sennheiser HD800 | Beyerdynamic DT-990 Pro (600 Ω)

    The rated output power of the tested amplifier is so high that it could successfully drive loudspeakers. But there are headphones, which are equally difficult loads, for example HiFiMAN HE-6. Low efficiency means that they are notoriously under-driven. Lupi held them on a short leash, meaning there was no question of lack of power. The sound was very clean, fast, which are the inherent features of these cans. However, despite the strong bass of the amplifier, the headphones remained at a fairly high tonal level, because that what they are. The bass was well controlled, pure, lively, but it lacked the richness, which the HE-1000 V2 delighted me with. The HE-6s sounded best with the switch in the "Low" position.

    The Sennheiser HD800 dynamic headphones also require good amplifier. Unlike planar HiFiMANs, however, they are easier to drive. It turned out that their tonal balance is similar to that of the HE-6, but with a lower midrange playing a bigger role. Lupi greatly presented advantages of these headphones, usually disappearing in the coloration and lack of a "drive" - here there was everything one can expect from such a system. In this case the headphones sounded best with the switch in the "High" position.

    And finally, a studio reference, 600-ohm Beyerdynamic headphones, a unit from almost 20 years ago, the same was used back then by the sound engineers recording the performances of Krzysztof Penderecki, with whom I had the opportunity to cooperate. I have to say that I only once I heard the DT990 Pro headphones performing so well, and it was with a professional amplifier in a studio. But even then it was not a well-balanced sound, as it was in this case. Switch was in the "High" position.

    This is not the most resolving amplifier, but it has an incredible vitality and speed, which causes the sound to have a lower tonal balance, it is also denser and the bass is more "present". The Sennheiser and HiFiMAN headphones controlled this range better, but the musical experience was more complete with Beyerdynamics. As it turns out, it is not that the Fezz Audio amplifier imposes its vision of sound on the headphones it is used with, it does not close the sound of the recordings in one format. Both headphones and recordings speak with their own voice, only that it is saturated with Omega Lupi's DNA.

    In comparison with the most expensive headphone amplifiers I know and those I own, the Polish device is less resolving and does not go so deeply into the sound, into the form of instruments, like - Ayon Audio HA-3. It builds sound rather on the axis and that's where the window of momentum I've mentioned opens up, while Ayon and Octave V16 Single Ended open the space also on the sides. Or maybe it's something else, maybe Fezz Audio more accurately showed the differences in this respect between different realizations? It can also be true. But the impression remains that the Fezz Audio amplifier delivers a stronger, more emphatic center of the stage.


    Ω Lupi sounds sensationally well. It delivers a low sound saturated with colors and rich with momentum. It energized the bass and modeled it, without the ultimate control at the very bottom. However, it did not really bother me – at least until I compared it with a much more expensive headamp. The resolution is very good, really fantastic and only single-ended designed using best tubes go even further. But when we take the price into consideration, that's a Burgundy sensation, which deserves to be honored with a BURGUNDY Fingerprint :)

    Outside | The Lupi amplifier looks like a classic integrated amplifier. It is because of its flat main body with electronics inside and tubes at the top and a higher screen at the back covering the output transformers. The transformers are manufactured in house, by, from which the Fezz Audio brands derives. Designers could therefore design them exactly for a particular amplifier. The power transformer and the choke are made in house - both on a toroidal core.

    On the front panel there are two silver knobs – volume control and output impedance switch. The power switch is on the rear panel, which is not particularly convenient. The tubes used in this project are PCL86 triode-penthodes that look similar to the popular EL84 pentodes. They work in a push-pull circuit in the AB class. The screen behind them has a beveled front, making it look lighter than usual. The segment with tubes can be covered with a safety grid with which - it's a rarity - Ω Lupi looks just as nice as without it.

    Inside | The electronic circuit is assembled on a small printed circuit board. I found there coupling capacitors from the Polish company Miflex. I do not know if you remember, but this manufacturer located in Kutno also produces capacitors for GigaWatt (more HERE). It's a good sign – these are great capacitors, now all Miflex has to do is to develop their range and keep improving the quality. The model used in Omega Lupi has polypropylene spacers and is marked with the MKP-01 designation. The other capacitors used here are also of high quality, as they come from the Japanese company Nichicon.

    The signal from input sockets (nice ones) located on the rear wall is send through long shielded interconnects to the potentiometer on the front panel. To tell you the truth, I do not know why it was placed on the left side, while for right-handers it would be more convenient to place it on the right, and the interconnects could be half as long. After the attenuation, the signal is transmitted using another set of interconnects to the board, to the grid of the first triodes. Interesting fact - the potentiometer is equipped with a motor for remote control. There is no remote control though because it would increase the cost of the device.

    The power supply is based on a large toroidal transformer and a choke - also featuring a toroidal core. Their cores were immersed in a resin to reduce vibrations. Toroidal output transformers are at the top, under the black painted part of the housing that shields them.

    It's a clean, solidly assembled design using very good components. But, let's repeat, the main strength of Fezz Audio amplifiers - including Omega Lupi - are excellent transformers.

    Technical specifications (according to manufacturer)

    Type: stereo vacuum tube headphone amplifier
    Max. output power: 2 x 250mW
    Circuit type: Push-pull AB1 Class
    impedance: 32-600Ω
    inputs: 1 x RCA
    outputs: 1 x RCA
    THD < 0.3%
    Frequency response: 20Hz-120kHz (-3dB) re
    Power consumption: 90W
    Weight nett: 9.5 kg
    Dimensions: 340x355x150mm



    - Turntable: AVID HIFI Acutus SP [Custom Version]
    - Cartridges: Miyajima Laboratory KANSUI, review HERE | Miyajima Laboratory SHILABE, review HERE | Miyajima Laboratory ZERO (mono) | Denon DL-103SA, review HERE
    - Phono stage: RCM Audio Sensor Prelude IC, review HERE

    - Compact Disc Player: Ancient Audio AIR V-edition, review HERE

    - Line Preamplifier: Polaris III [Custom Version] + AC Regenerator, regular version review (in Polish) HERE
    - Power amplifier: Soulution 710
    - Integrated Amplifier: Leben CS300XS Custom Version, review HERE

    - Stand mount Loudspeakers: Harbeth M40.1 Domestic, review HERE
    - Stands for Harbeths: Acoustic Revive Custom Series Loudspeaker Stands
    - Real-Sound Processor: SPEC RSP-101/GL
    - Integrated Amplifier/Headphone amplifier: Leben CS300XS Custom Version, review HERE
    - Headphones: HIFIMAN HE-6, review HERE | HIFIMAN HE-500, review HERE | HIFIMAN HE-300, review HERE | Sennheiser HD800 | AKG K701, review (in Polish) HERE | Ultrasone PROLine 2500, Beyerdynamic DT-990 Pro, version 600 - reviews (in Polish): HERE, HERE, HERE
    - Headphone Stands: Klutz Design CanCans (x 3), review (in Polish) HERE
    - Headphone Cables: Entreq Konstantin 2010/Sennheiser HD800/HIFIMAN HE-500, review HERE

    - Portable Player: HIFIMAN HM-801
    - USB Cables: Acoustic Revive USB-1.0SP (1 m) | Acoustic Revive USB-5.0PL (5 m), review HERE
    - LAN Cables: Acoustic Revive LAN-1.0 PA (kable ) | RLI-1 (filtry), review HERE
    - Router: Liksys WAG320N
    - NAS: Synology DS410j/8 TB
    System I
    - Interconnects: Acrolink Mexcel 7N-DA6300, review HERE | preamplifier-power amplifier: Acrolink 8N-A2080III Evo, review HERE
    - Loudspeaker Cables: Tara Labs Omega Onyx, review (in Polish) HERE
    System II
    - Interconnects: Acoustic Revive RCA-1.0PA | XLR-1.0PA II
    - Loudspeaker Cables: Acoustic Revive SPC-PA

    System I
    - Power Cables: Acrolink Mexcel 7N-PC9300, all system, review HERE
    - Power Distributor: Acoustic Revive RTP-4eu Ultimate, review HERE
    - Power Line: power cable Oyaide Tunami Nigo (6m); wall sockets 3 x Furutech FT-SWS (R)
    System II
    - Power Cables: Harmonix X-DC350M2R Improved-Version, review (in Polish) HERE | Oyaide GPX-R (x 4 ), review HERE
    - Power Distributor: Oyaide MTS-4e, review HERE
    - Stolik: SolidBase IV Custom, read HERE/all system
    - Anti-vibration Platforms: Acoustic Revive RAF-48H, review HERE/digital sources | Pro Audio Bono [Custom Version]/headphone amplifier/integrated amplifier, review HERE | Acoustic Revive RST-38H/loudspeakers under review/stands for loudspeakers under review
    - Anti-vibration Feets: Franc Audio Accessories Ceramic Disc/ CD Player/Ayon Polaris II Power Supply /products under review, review HERE | Finite Elemente CeraPuc/ products under review, review HERE | Audio Replas OPT-30HG-SC/PL HR Quartz, review HERE
    - Anti-vibration accsories: Audio Replas CNS-7000SZ/power cable, review HERE
    - Quartz Isolators: Acoustic Revive RIQ-5010/CP-4

    - FM Radio: Tivoli Audio Model One