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Review of the Fezz Audio Omega Lupi Evo tube headphone amplifier

04.04.2024 08:49

The Fezz Audio line of tube amplifiers appears to cover a wide range of devices, each of which has its own uniqueness, not only in name, but also in technical characteristics and sonic character. The use of PCL86 tubes in the Omega Lupi Evo amplifier is an interesting choice, as these tubes were originally designed for use in television equipment, but due to their high performance characteristics have also found use in audio amplifiers. This highlights Fezz Audio's unconventional approach to creating its products.

The original design of the amplifier, capable of driving headphones with an impedance of up to 600 Ohms, makes it extremely flexible in use, which is important for audiophiles and professionals who have in their arsenal a variety of headphones for a wide variety of tasks. The high-quality Toroidy transformers used in the amplifier also play a key role in shaping the sound image, offering clear and detailed sound, an important quality in a tube amplifier.

The design of Fezz Audio devices, combining retro elements and modern technology, creates a special charm and makes them stand out from other audio devices. This approach not only draws attention to the product, but also emphasizes the brand's personality in the market.

The presence of sound coloring mentioned in relation to the Omega Lupi Evo is an interesting feature, as many audiophiles are looking for devices that can add a special character to their favorite music. This suggests that Fezz Audio does not strive to create a completely neutral sound, like many other manufacturers, but offers listeners a unique audio experience, which is certainly valued in the world of audiophilia.

Overall, Fezz Audio continues to impress with its approach to creating unique audio devices, demonstrating attention to detail, innovative design solutions and a commitment to creating an outstanding audio experience for its users.


Model nameFezz Audio Omega Lupi Evo
Device typestereo tube headphone amplifier
Circuit designpush-pull, class AB
Bias current settingautomatically
Maximum output power2×250 mW
Frequency range20 Hz — 120 kHz (−3 dB)
Supported headphone impedance32—600 Ohm
Headphone outputjack 6.3 mm
Power consumption90 W
Weight9.5 kg
Dimensions340×355×150 mm


In addition to the device itself, the Fezz Audio Omega Lupi Evo delivery kit includes a number of components and accessories that will be useful during the preparation of the amplifier for operation and its operation:

  • Fezz Audio Omega Lupi Evo tube headphone amplifier
  • power cable
  • PLC86 lamps — 4 pieces
  • fabric gloves for installing lamps
  • protective cover for lamps


The design of Fezz Audio amplifiers is characterized by a single concept: metal housings, visually accessible tubes and expressive retro style elements. Omega Lupi continues this tradition with a particularly attractive design that has already won the prestigious Red Dot Award for design. The color palette has expanded from previous models, including not only the brand's standard black, white, red and burgundy shades, but also adding new ones — silver, dark green and a unique golden shade called «sunshine», which is not too dark. This makes it possible to choose an amplifier that will fit perfectly into any interior, emphasizing that tube equipment often serves not only for playing music, but also as a decorative element. For testing, we had a model with a classic black case.

Omega Lupi Evo comes partially disassembled — we will present it assembled, but it is worth noting that before first use you need to install the lamps in their places, connect the mains cable and secure the protective cover using two screws that can be easily tightened by hand. If you don't have small children or animals in your home that could damage the amplifier, you can use it without the enclosure. However, in this case, the use of a casing is preferable, since the amplifier with it looks no less attractive, and maybe even better, than without it.

The lamps are supplied separately, and they are marked with minimal markings — only a number without indicating the manufacturer or other information. The creators of the amplifier assure the high quality of the tubes and that they come in matched pairs, which gives reason to trust their words.

The boxes with lamps are numbered, the corresponding numbering is on the slots for them on the top cover of the amplifier — the installation process is simplified as much as possible.

Protective covers for transformers are installed on the top of the amplifier. The case has a matte finish that not only looks stylish, but is also resistant to touch stains. The rear panel contains RCA audio inputs, a port for connecting to the mains, and a switch. For models equipped with Bluetooth, there are special places for the antenna and wireless connection switch, which in our copy are covered with plastic covers.

The bottom features ventilation holes and tapered feet to ensure the Fezz Audio Omega Lupi Evo sits securely on a horizontal surface.


As noted at the outset, the Omega Lupi amplifier uses the rather unique and attractive PCL86 tubes, which are a combination of a low power triode and a high power pentode. These tubes found widespread use in the manufacture of the latest generations of tube televisions in the 1980s, but were initially rarely chosen for use in amplifiers. However, over time, for various reasons, including economic ones, the attitude towards them in the audio industry changed, and amplifiers based on PCL86 began to be produced and popularized.

In the Omega Lupi amplifier, the triode sections of these tubes are used as a preamplifier and driver, while the pentode sections of the two tubes are connected in a push-pull circuit, forming the output amplifier stage. This ensures the creation of an amplifier in class AB1 with a push-pull architecture. The structure is simple and elegant, with relatively compact dimensions, but at the same time capable of offering a noticeably colored sound, the details of which we will examine in the corresponding section of the review.

Amplifiers under the Fezz Audio brand are notable for their unique hand-assembly, which is actively discussed in the comments under our previous reviews. It must be admitted that the appearance of the printed circuit boards leaves much to be desired — as our readers have noted more than once, such work would hardly be highly appreciated in a school radio club. On the other hand, there is an opinion that these visual aspects do not affect the functionality of the devices, and most users are unlikely to ever see the insides of the amplifier, while the appearance of the products is of a high standard. Both points of view deserve attention, but the hope remains that in any product, especially in the premium segment, there should be perfection in everything — both in external design and in internal structure. It's clear that the amplifiers have been put together with care and attention to detail: the wires are neatly routed and the components are securely secured. In addition, a small personal touch was added to the side of the case — a sticker with the names of the assembler and tester of this device, which adds a special charm to the amplifier.

Transformers are an integral part of the design of push-pull amplifiers, and here it is appropriate to remember the origins of Fezz Audio. The Toroidy company operates in Poland, specializing in the production of toroidal transformers for more than two decades. Their products are used in high-end Hi-End devices from such well-known brands as Aurender, B.Audio, Ancient Audio, Baltlab, Lampizator, Amare Musica, Audio Valve and others. At a certain point, the company's management, consisting of the founder and his two sons, whose last name is Lachowski, came to the decision that, having such an important component, they were ready to create their own tube amplifier. This is how the Fezz Audio brand, which we know well today, was born.

Thus, the transformers used in the amplifiers are not just high quality, but are among the best on the market. The developers even decided to update the markings on the transformer casings, adding their name to the Toroidy brand. This step shows that they are proud of the product they are creating and want to emphasize its high quality.

The quality of the components remains high, in particular, it is worth noting the capacitors from Samwha Capacitor Group — one of the oldest Korean companies specializing in the production of passive electronic components.

It is also worth paying attention to film capacitors from the German manufacturer Wima, founded in 1948.

Connection and operation

On the rear panel of the Omega Lupi Evo there are two sets of RCA connectors that allow you to feed an audio signal into the amplifier and transmit it further, for example, to another amplifier to which the speakers are connected.

On the right side of the rear panel there is a connector for the power cable and a switch. There is also a «signal ground» switch, which in most cases is recommended to be left on.

On the left side of the front panel there is a volume control knob — a potentiometer with a smooth stroke and limited rotation angle. Its operation is correct, does not add unnecessary noise, and rotates with pleasant effort. Nearby is the only headphone jack — a 6.3 mm jack.

On the right side of the panel there is a selector that allows you to adjust the output characteristics of the amplifier depending on the impedance of the connected headphones. There are three positions in total: Low for headphones with an impedance of 32 Ohms, Mid for headphones with an impedance in the range from 32 to 150 Ohms, and High for high-impedance headphones up to 600 Ohms. If you select the right mode, volume adjustment will be smooth, and the background noise level will remain at an acceptable level.

It should be noted that the Fezz Audio Omega Lupi Evo amplifier has a huge volume reserve, even when connecting high-impedance headphones. There is no doubt about its ability to work even with the most “difficult” models that may be in the arsenal of high-quality sound lovers.


For testing, we had a choice of several magnetic planar headphones from Audeze, each model of which fully corresponded to the level of the amplifier being tested. Our choice fell on two models that differ noticeably in sound, which allowed us to examine the Fezz Audio Omega Lupi Evo from different angles. The flagship model Audeze LCD-5 is distinguished by restrained bass, detailed mids and an interesting emphasis on high frequencies. While the Audeze LCD-X headphones offer more pronounced bass with balanced highs, while maintaining the crisp mids that characterize the entire Audeze range.

It is worth noting that when we talk about the features of various Audeze models, we mean the nuances of sound, and not the obvious “humps” in the frequency response that are often found in some headphones. All of the manufacturer's devices have a balanced sound, and small differences in their tuning create a unique «character» without making one model better or worse than another.

For listening, we chose devices from well-known manufacturers, the quality of which was beyond doubt. Particularly noteworthy is the appearance of the Ferrum Audio Erco headphone amplifier and DAC in our test setup. The «tube color» characteristic was noticeable in the early stages of listening, but over time the ear adapted and the impression became less pronounced. Switching between an amp with and without tube coloration helped us better appreciate the subtle nuances of the sound. The presence of Erco in the system also allowed us to conduct several interesting comparative tests, the results of which we will present in the final part of the review.

So, our test setup included:

  • Fezz Audio Omega Lupi Evo amplifier
  • Audeze LCD-5 and LCD-X headphones
  • Network audio player Aurender N150
  • Ferrum Audio Hypsos power supply
  • Ferrum Audio Wandla DAC/preamplifier
  • Amplifier-DAC for headphones Ferrum Audio Erco

Let's start by discussing the sound in general before moving on to the listening experience of specific tracks. It is recommended to keep the gain level to a minimum to avoid background noise. The Fezz Audio Omega Lupi Evo amp has a recognizable sound color, but sounds a little harsher than expected from a tube amp, likely due to the nature of the PCL86 tubes. The low frequencies are slightly muted, which accentuates the mids, especially the lower part. The sound is balanced, but with character that you may or may not like — so it is recommended to listen to the Omega Lupi Evo before adding it to your setup.

Now let's move on to the impressions of listening to specific tracks.

  1. Stacey Kent — Under Paris Skies: Jazz sounds especially great on a tube amp. The voice of American singer Stacy Kent sounds sophisticated and emotional, adding to the atmosphere of the composition. This is a great choice for enjoying music on the Fezz Audio Omega Lupi Evo.
  2. Cory Weeds — Thedia: This jazzy track perfectly captures the richness of the instrumental sounds. Saxophonist Corey Weeds and his orchestra create a wonderful atmosphere that can be fully experienced through a tube amp and LCD-5 or LCD-X headphones.
  3. The Beatles — Now And Then: Despite its unusual nature, the new Beatles track sounds attractive and exciting. Modern technologies have made it possible to bring recording to high quality, and it sounds great on the Fezz Audio Omega Lupi Evo with LCD-5 or LCD-X headphones.

Overall, both amplifiers and both pairs of headphones offer a unique audio experience, and choosing between them depends on your sound preferences and style of music.

Let's take a look at a few popular tracks and see how they sound on two different headphones paired with tube and non-tube amplifiers.

  1. Miley Cyrus — Flowers: Miley Cyrus' vocals sound great on both the LCD-5 and LCD-X. The LCD-5 gives the sound a velvety feel and maintains balance, especially in the low-frequency range, which is especially important for pop music. On the other hand, LCD-X emphasizes the rhythm of the track and makes it more danceable.
  2. Skrillex — Ratata: Both headphones handle electronic music well, but have some differences in sound. The LCD-5 retains detail and makes the sound more tube-like, while the LCD-X adds a stronger bass accent and emphasizes the rhythmic aspects of the track.
  3. Sigur Rós — Blóðberg: This composition requires careful listening to reveal all its emotional nuances. LCD-5s allow you to hear a richness of detail and create a soft, sweet sound, while LCD-Xs add more epicness and make the track more emotionally rich.
  4. Passenger — Let Her Go (Feat. Ed Sheeran — Anniversary Edition): Both versions of the amps, the LCD-5 and LCD-X, produce vocals that sound nice and clear. LCD-X add more volume and depth to a track's sound with stronger bass.

Overall, both headphones and both amplifiers offer their own unique sound characteristics, and the choice between them depends on the listener's preferences.

As was revealed in previous testing, tube sound is characterized by the presence of harmonic distortion. Below are graphs that clearly show that the level of these distortions is significantly higher in the Fezz Audio Omega Lupi Evo, although the emphasis on even harmonics is less pronounced than usual with tube amplifiers. This explains some of the harshness of the sound of this model, which differs from traditional tube sound, and is also associated with the design features of the tubes installed in it.

Fezz Audio Omega Lupi Evo
Ferrum Audio Erco

Let's do the same with LCD-X. It can be seen that the headphones are slightly bassy, but in the case of the Fezz Audio Omega Lupi Evo they “pull up” the sound of the low-frequency range to a quite reasonable level.

The same applies to distortion — the Fezz Audio Omega Lupi Evo successfully adds color to the sound while maintaining the ability to deliver high-quality playback with virtually any headphone in an audiophile's audio arsenal.

Fezz Audio Omega Lupi Evo
Ferrum Audio Erco


The Fezz Audio Omega Lupi Evo amplifier is a device with a unique character that can either impress or disappoint. However, its versatility and ability to fit seamlessly into a variety of setups make it an attractive choice for a wide range of audiophiles. With its interesting design and distinct sound color, it brings new colors to the music listening experience, especially for those looking for variety in the sound of their audio system.