Reviewer: Srajan Ebaen
Financial interests: click here
Sources: 27" iMac with 5K Retina display, 4GHz quad-core engine with 4.4GHz turbo boost, 3TB Fusion Drive, 16GB SDRAM, OSX Yosemite, PureMusic 3.01, Tidal & Qobuz lossless streaming, COS Engineering D1 & H1, AURALiC Vega, Aqua Hifi Formula, Fore Audio DAISy 1, Apple iPod Classic 160GB (AIFF), Astell& Kern AK100 modified by Red Wine Audio, Questyle QP1R, Soundaware Esther Pro, Soundaware D100 Pro SD card reader
Headphone amps: COS Engineering H1, Bakoon AMP-12, Vinnie Rossi LIO, Questyle CMA-800R (x2), Eversound Essence
Headphones: Final Sonorous X, VI & III and D8000 [on review]; HifiMan Susvara [on loan], HE-1000 & HE-6; Sennheiser HD800; Audeze LCD-XC and LCD-2v1; Meze Neo Classic
Power delivery: Vibex Granada/Alhambra or Furutech RTp-6
Review component retail: €1'999 [incl. 23% VAT]

Another email, another brand. "We are a boutique tube amplifier manufacturer based in Lubliniec, Poland. We specialize in fully hand-built headphone and speaker amps. Would you be interested in reviewing our OTL Euforia model based on the 6SN7/6AS7G?" That was signed Lukasz Feliks, head of sales, Feliks Audio. So, Poland had struck again. Little surprise there. Peter O'Malley, a local building contractor, recently returned from many prosperous years in the UK to County Mayo. He told us about rebuilding his crew in Ireland. "The Poles are terrific workers but very ambitious. Unlike the Chinese who are very loyal and who in the UK worked with me for decades, the Poles will learn everything there is to learn and work hard. But they always dream to one day set up their own shop. They're very industrious. Eventually they all leave." I wasn't hiring so not worried. The rest I'd surmised already after two Warsaw shows many years ago. From subsequent review experience, I'd further learnt that Polish hifi brands can be very good for surprises. Recent awards came to Cube Audio and StavEssence. Clearly it was safer to accept this solicitation than miss out on a potentially promising discovery.


After I had accepted with a laconic "why not?", Lukasz went away for a bit before returning with "I waited for our revised 2018 models to become available as there are some nice changes. If we provide you a unit within the next few days, would you still be able to review and publish before the year's end?" Having a month to comply, another affirmative was in order. So was a third when Lukasz stressed over "I have the amp ready for shipping but cannot see from the address you provided what the street name/number and post code are." Rural west-coast Ireland is like that. Like clockwork, it trips up first-time senders. And like clockwork, our antiquated address system delivers without a hitch. For Feliks Audio then, it was three strikes and you're in.


Whilst our address seemed admittedly spotty—there are 200+ homes in our area yet ours isn't identified by anything other than our names—I told Lukasz that we would need a lot more information about him, his company and the amp so reader imaginations would go to the right place. Where our postman knows everyone by name, none of us had ever yet set foot in Feliks land. Specs can only tell part of that story.


Here said chapter covers 8Hz-75kHz bandwidth ±3dB with output power of just ¼ watts. Input impedance is 100kΩ. Output impedance remains unspecified but the grid resistance of a twin-triode 6N13S is about 460Ω. Internal wiring is pure Teflon-coated silver. Other listed parts include Mundorf and Nichicon caps, Dale and Caddock resistors. Where aside from raw power things get skimpy is output socketry. For cans it's just a 6.3mm port. A 4-pin XLR from this single-ended circuit would require balancing transformers. Perhaps the OTL concept defied those? There is a line-out for minimalist preamp use and a single RCA input pair for your source of choice.

Stock photos not yet updated to the TII series Psvane tubes used in the 2018 edition.
The provided tubes are matched new-old-stock 6N13S/ECC230, the driver tubes upgraded Psvane CV-181TII Gold versions. Dimensions of the amp's metal casing are 31 x 20.5 x 17.5cm. Its weight is 6kg. Peace of mind comes from a 3-year warranty. Whilst the specs cite support for 32-600Ω loads, the frequency response and 0.4% THD values are specific to 300Ω. This should have owners of 30-50Ω planars wonder what this amp will do with their headphones. With sundry Audeze, HifiMan and MrSpeakers on hand, I'd find out. But given that Feliks Audio sell direct and worldwide, customer interactions too will be directly with them. Then why not have more in-depth information available? Wouldn't prospective buyers want to know output power into specific load Ω, overall voltage gain, input sensitivity and, critically, noise figures for potential IEM happiness or high-sensitivity over-ears like our Final Sonorous models? Shouldn't a direct-seller's website anticipate all reasonable queries a priori? With comprehensive tech and background questions covered, email traffic will then primarily deal with orders; or trouble-shoot issues and the occasional repair or upgrade. Yet neither website nor owner's manual went beyond basics. That and featurization—why not at least a 3.5mm output—struck me as potential improvement areas.
To reaffirm, Euforia's big canister behind the tubes would contain only a power trafo plus possibly a choke or two but no output iron. Your headphones connect to the 6N13S through coupling caps instead. That's the definition of an OTL. It's shorthand for output-transformer-less. Hence there are no magnetic turns to downshift the tubes' impedance. It's why for speaker use where 8Ω acts as a generic value, OTL amps tend to multi-parallel their output bottles. Not only does it add power, it lowers output Ω without a transformer.


The promised OTL advantage is sonic. One is supposed to hear more speed, immediacy and openness; more pure tube qualities not modified by the effects of transformer windings, phase shift and bandwidth limitations. If you're wondering why Shuguang's 6SN7 don't look the all shiny and transparent part, "our patented crystallized carbon grey coating inside the glass bulb of the TII series improves absorption of random electrons and dissipates heat more efficiently to further enhance operational stability." The 'gold' of the nomenclature refers to 24K grid wiring. And the maker's logo is now on the base, no longer the glass. These tubes are a solid $290 retail value.


The advertised crossfeed circuit wants to combat what some feel is an unnatural aspect of headfi: that each ear only hears its own channel. Remember, during speaker playback or live music, each ear hears both speakers and all the performers. Crossfeed circuits then do exactly what their name suggests. They deliberately add counter-channel signal to each ear. How much and across what bandwidth tends to be the make-or-break aspect of crossfeed appeal. Should you not agree with Feliks Audio's dose, you can always defeat it. In the above stock photos, I simply couldn't make out its switch but the owner's manual showed it to be on the rear next to the mains rocker. Now I was curious. What would Feliks come back with for my generic request on 'more' information? I deliberately asked for nothing specific to learn what they considered relevant to prospective shoppers. Perhaps over the years my long journalist's nose had grown to unseeming Pinocchio proportions. Perhaps nobody really cares about any of the stuff I'm usually on about. In which case it was high time to cut back and take it easy. Where was that rocking chair and cuppa tea? Cue up some tunes already!


About themselves, Feliks Audio added that they were "a boutique manufacturer with over 20 years of experience. All our products are in-house engineered, tuned and assembled. Originally focused mainly on custom amplifiers tailored to a client's needs, over time we developed many innovative sophisticated audio solutions which gained us valuable knowledge and experience across a broad range of applications. Our products offer a perfect blend of passion for honest sound, great attention to technical details and beautiful finish. We follow design simplicity by minimizing the number of parts in the signal path. This ensures that the sound is pure and true." I learnt nothing more about the amp. In case readers were curious about 30/60/100Ω power ratings, output Ω, voltage gain, S/NR and residual noise figures, crossfeed bandwidth and what distinguishes the Euforia from the Elise model other than crossfeed, 50mW higher power and upgraded tubes, I sent out another query, this time very specific. "Usually not many customers ask for that. What people are very curious about are real-life pairings with different sorts of headphones. Regarding Euforia vs Elise, this indeed is a common question. Measured with a max 1.8Vrms input where THD falls below 0.5%, Euforia will deliver 0.13 watts into 32Ω and 300Ω, 0.2W into 100Ω and 0.08W into 600Ω. Voltage gain is 20dB and output impedance 20Ω. S/NR is about 97dB. Examples of headphones our customers really like with Euforia are Focal Utopia, ZMF Eikon, Audeze LCD2, Sennheiser HD800/s, BeyerDynamic T1.


"And for a small anecdote, during our London CanJam exhibit this year, we used Focal's Utopia and Elear. Euforia proved such a great match particularly with Utopia that Focal's senior manager asked that Euforia be their reference tube amp for all future show exhibits. Between Euforia and Elise, Euforia is much more dynamic. Some may almost think transistor amp in that regard, with a really wonderful but neutral sound which still is undeniably 'tube'. Elise on the other hand has more of a typical warm tube sound and acts more laid back and less dynamic. Elise's 10Hz-60kHz bandwidth is also a bit less and output power for Euforia is 20% higher. This is a very power-effective amp. Though we could have pushed power output further, our tests showed that this was more than enough to drive most headphones. Euforia's hand-made internal wiring is pure silver in Teflon coating. This improves the treble and detail while other parts choices balance out that effect to avoid the harshness which some silver wires can exhibit. Capacitors and resistors also are upgraded over Elise and the crossfeed function is exclusive to Euforia. Different also is the power transformer in a revised casing that's even better at shielding from RFI. Finally the driver tube upgrade to Psvane CV181-TII as the best current-production 6SN7 available was a significant sonic step up."