Selected Comparisons
Unfortunately, Feliks Audio amplifiers such as the original Euforia and the 20th Anniversary Edition were reviewed by Mike so, below is a broader sample of some alternatives including Feliks Audio’s flagship Envy.
All comparisons for the EUFORIA evo were completed using a Holo Audio Spring Wildism DAC as well as the iBasso DX320 MAX Ti 3.5mm LO portable alternative combined with the ZMF Headphones Atrium open-back edition and the Focal Utopia 2022 headphones.
Auris Audio HA-2SF
$2499
The Auris Audio HA-2SF was launched in 2021 and superseded the now-discontinued HA-2SE desktop tube headphone amplifier. It was also our Top Gear Award 2021 winner. You can read our full review of the HA-2SF here.
Technical
The HA-2SF is a SET headphone amplifier with a preamp output and a single output-coupled transformer. The EUFORIA evo is a transformerless OTL amplifier though it also has preamp capability.
Both use single-ended topologies but come equipped with both 6.35mm and XLR PO outputs for convenience rather than actual balanced output. The HA-2SF, however, does have a +30 dB gain switch and XLR inputs on the rear so whilst still SE it can accept XLR inputs that maybe have a stronger Vrms output from the corresponding source.
It also possesses an additional 3-stage impedance selector switch for matching headphones’ impedance from 32Ω to 600Ω. The EUFORIA evo lacks that type of control though OTL owners are likely to buy it based on its performance on higher loads or for efficient planars.
The HA-2SF tube configuration is also quite different. It uses four JJ Electronics ECC99 9-pin double triode power tubes and a single input JJ Electronics ECC82 tube. The ECC82 is a 12AU7 medium gain pre-amplifying double triode design whereas the ECC99 driver tubes have excellent current handling capability making this suitable for planar headphones.
The EUFORIA evo uses a matching set of PsVane CV181 MK2 “Gold” drivers combined with a pair of 6N13S (NOS) power tubes and are a little more expensive to acquire with the PsVane choices offering gold pins, (not present on the HA-2SF alternatives), for additional conductivity and Teflon bases for heightened durability.
The power gap between these two on paper at 300Ω is around 215mW for the HA-2SF and 280mW for the EUFORIA evo. I can assure you both can handle 300Ω dynamic driver headphones with relative ease. However, the HA-2SF seemed to have more headroom to handle less efficient planar headphones.
Design
Two excellent examples of very contrasting design languages that look amazing in their own right.
Now if you are into retro organic colors, a dash of wood, and real leather then the HA-2SF is one of the finest made amplifiers in that category. If you are after something more modern yet with a hint of 1940s noire thrown in and definitely more compact then the EUFORIA evo fits the bill.
I would say the larger form factor of the HA-2SF demands more space and its own rack shelf, especially with its dedicated external linear PSU unit and power cable. The EUFORIA evo should be a bit more flexible in terms of shelving space but because of its OTL design, it will generate more heat than the HA-2SF and should be given plenty of space all the same.
The HA-2SF also comes with a lot more ‘bling’ so to speak with its LED-lit passive logarithmic VU-meters and some glow ‘enhancement’ under the main tube array on the top. It’s a topical one, some love it, and some might prefer the more discreet tube glow, power light, and nothing else from the EUFORIA evo.
Both come with flexible PO ports with the inclusion of a standard 6.35mm socket as well as 4-pin XLR though bear in mind both have the same power output rating as these are single-ended amplifiers.
The rear does present some advantages to the HA-2SF with its 2 dual RCA SE source inputs and one 3-pin XLR though both offer dedicated pre-amp dual RCA outputs.
They also differ in their respective ‘enhancements’ with the HA-2SF offering a 30 dB gain switch. Whereas the EUFORIA evo instead introduces a unique crossfeed option for bass imaging and perceived weight for older dual mono recordings.
Performance
I tested the 80Ω Utopia 2022 and the 300Ω ZMF Headphones Atrium in this comparison.
The HA-2SF does have more headroom in terms of outright power at lower impedance levels. The EUFORIA evo got pushed a lot further and with no impedance switch that allows the HA-2SF some additional flexibility to enhance dynamics or opt for a softer but flatter performance. Despite the power difference, I felt both amplifiers had no issues with either headphone.
The HA-2SF offers a more neutral presentation, both in terms of coloration and staging dimensions. If you are after the classic tube tonal coloration and an ambient or slightly relaxed but larger staging quality then the EUFORIA evo is going to do better.
It delivers a richer fuller tone for me, slightly less treble in both headphones but in return, and especially with the Focal, I felt it was the more spacious in terms of imaging.
The HA-2SF is punchier, though more neutral on the sub-bass in terms of warmth and presence. Mids seem a shade more intimate and center-focused as a result which does not suit the full-bodied sound of the Focal midrange sounding comparatively congested.
The EUFORIA evo is not as aggressive, a bit more rounded in tone with a little less treble sparkle. It will diminish sibilance and introduce more body but at a more languid pace.
However, it also does better with the imaging side and is my preferred fit for Utopia 2022 whose narrower staging quality benefits from a more atmospheric quality.
The Atrium was a beautiful pairing with the EUFORIA evo casting excellent depth and height with a smooth tonal coloration. Of the two, the vocals were more euphonic and pleasing to my ear. However, if you need more mid-bass energy and a stronger treble the HA-2SF is more suited.
Cayin HA-300MK2
$4399
Moving up the ladder a little, the HA-300MK2 from Cayin was launched last year and was also a Top Gear Award 2022 winner. You can find our full review of the HA-300MK2 here.
Technical
Unlike the OTL design of the EUFORIA evo, the HA-300MK2 is a transformed coupled Class-A SETA and a single-ended triode amplifier for speakers. The SETA topology is a favored one for Cayin over push-pull designs for their generally smooth-sounding presentation.
The tube configuration is significantly different also with the HA-300MK2 closer aligned to the ENVY in its choice of tubes than the EUFORIA evo.
The drivers are a pair of matched Tung-Sol 6NS7GTB dual-triode tubes, favored for low noise and a rich tone, and a matched pair of Gold Lion Genelex PX300B tubes for power to closer align to the Cayin ‘house sound’. The PSU is driven by a quad set of NOS RCA 22DE4 rectifier tubes.
Both amplifiers are single-ended, however, the HA-300MK2 can offer a balanced output driven through its dual output transformer design which will generate significantly more current output than the EUFORIA evo. It can also offer a 3-stage impedance selector to better match the output impedance and varying loads of a wide range of headphones.
That will give it significantly more output power for difficult-to-driver planar headphones as well as potentially match the EUFORIA evo for voltage-intensive dynamic driver alternatives.
If you are wondering where the additional cost is between the EUFORIA evo and the HA-300MK2 then the majority of it is in the above and not just the bigger externals.
Design
The HA-300MK3 amplifier is much bigger than the EUFORIA evo. At 29kG combined for both the amp and PSU, it requires a significant amount of rack or desk real estate space compared to the tidier and more compact EUFORIA evo.
That being said, the EUFORIA evo is an OTL design and will generate plenty of heat. Not that the Cayin is cold by any means but space for both to vent is recommended.
Aesthetically, both have a closer design language compared to the Envy or the HA-2SF with their darker metallic plate designs. However, the sheer size and complexity of the HA-300MK2 means you get a heck of a lot of options, buttons, and switches on the front panel compared to the minimalist facia of the EUFORIA evo.
Some will value simplicity, others want to tweak so there will be fans of both. With the Cayin you get impedance choices, balanced 4.4mm/XLR or SE, as well as two passive VU meters and a small amount of LED illumination. With the EUFORIA evo, the front is clean save for the PO and Alps pot with the crossfeed option discreetly positioned on the rear.
One thing to note, the HA-300MK2 has no pre-amp capability. If you need that then the EUFORIA evo does have that advantage.
However, if you want a direct link to your speakers the HA-300MK2 can double as a speaker amplifier with a direct binding post on the rear panel and a switch to the front thus negating the need for a pre-amp if its 8W rating to both channels for speakers up to 8Ω is sufficient for your needs.
Performance
Testing with the Atrium, the HA-300MK2 was more holographic in its staging with a lot more width, improved separation, and more textured detail in vocal performances.
Of the two, it is the Cayin that is more immediate in the mids, more vocal bloom, and more sparkle giving it a very enveloping and effortless imaging quality to surrounding instruments.
I was also picking up a little more treble presence and airiness in the HA-300MK2 that gave the EUFORIA evo a comparatively darker quality to its performance. The HA-300MK2 is not a bright amplifier, but rather a little sweeter-sounding which helps flesh out the upper ceiling of the soundstage and gives some additional perceived space.
I will say something though about that EUFORIA evo bass body and presence at the very lower register with the Atrium. It does have a more fulsome sub-bass tone than the HA-300MK2 which just leaves off a little weight in favor of those amazing attention-grabbing mids.
That in turn gives the evo a smoother more voluptuous weighted midrange and vocal performance. One that dampens down on bright recordings and sibilance a bit more than the HA-300MK2.
You get a similar pattern also with the Focal Utopia 2022. The EUFORIA evo has a smoother more rounded, and slightly weightier note quality. It has a little more warmth and a longer decay in the lows, and a slightly darker set of highs.
The HA-300MK2 delivers more energy and imaging separation, airier mids, and a sweeter sparkle-enhanced set of highs. It has more immediacy, fleshing out more texture and detail in vocal performances.
Of the two, I tend to gravitate towards the EUFORIA evo for brighter recordings with leaner vocal mixes with the tested headphones and to the HA-300MK2 for more staging width, headroom, and improved resolution.
Feliks Audio Envy
$6499
The Feliks Audio Envy was launched last year and is the flagship tube headphone amplifier within the Feliks Audio line-up as well as a Top Gear 2022 Award winner. You can read our full review of the Envy here.
Technical
The most important distinction to make here is the pure-OTL design of the EUFORIA evo as a contrast to the Envy which is a 300B Class A headphones tube amplifier with a transformer-coupled output and a solid-state rectifier.
That does have ramifications for the type of sound, especially the bass, from these two amps so despite the price difference there may well be instances where some will prefer the tone and performance from the EUFORIA evo for their specific headphone pairings.
You get two tube configuration options with the Envy. The base option includes a set of Electro Harmonix Gold 300B power tubes whereas the Performance Edition includes a set of matching ‘gold-grid’ Fullmusic 300B triode power tubes. The sample we have here is the Performance Edition.
The second pair of tubes on the Envy is the exact same set of tubes used by the EUFORIA EVO which is a set of double triode PsVane CV-181-T MKII (6SN7) drivers. Both are Teflon based with gold tips.
The amplification design in both amplifiers is single-ended so whilst they offer XLR input and output their respective connections will not differ in regard to output ratings. That being said, the Envy is the more powerful of the two amplifiers with impedance selector features to help match varying loads.
So, whilst the EUFORIA evo is ideally suited to headphones with high voltage demands, it is the Envy that will bridge the gap to very demanding planar headphones such as the Susvara with around 6W for 32Ω and roughly around 4-5W for 50-60Ω loads.
Both amplifiers do use similar in-house wiring which includes “point to point” directly hard-wiring custom-made from a single-crystal copper (UPOCC) with Teflon isolation.
Design
If Feliks has proven anything from producing both the EUFORIA evo and the Envy, is that can diversify and produce some very different-looking amplifiers. These two are no exception.
The larger Envy has two heavily grained distinct sets of oiled woodblocks wrapped around a black chassis that ties the blocks together. The wood choice is beautiful with two choices available’ the above oak edition and a darker American walnut for an additional €200.
The EUFORIA evo is much the smaller of the two with a more discrete cedar brown finish on its metal chassis. There is a semblance though of a shared theme in both with that over-sized dominant potentiometer finish to their front panels.
However, as you can see from the picture, the additional impedance and input options of the Envy make it slightly busier looking on the front fascia.
Form-factors are considerably different with an 8kg weight difference. So, much like the other compared amplifiers, the Envy does require more space and a stronger shelf at that to house it properly. As with the other amplifiers, venting is crucial, possibly even more so with the EUFORIA evo whose OTL design generates a bit more heat.
You do get significantly more input options also on the Envy with 2 SE dual RCA and a single set of 3-Pin XLR inputs as well as a set of SE dual RCA and balanced pre-amp outputs. Unlike the EUFORIA evo, the Envy does not have that unique crossfeed feature.
Performance
You can tell right away that these two amplifiers are positioned quite differently and will probably appeal to different headphone owners.
No escaping that power of Envy paired with top-tier planar headphones. Headphones such as the Susvara and the Abyss Headphones Diana TC are driven beautifully on the Envy with excellent weight and dynamics.
These are headphones that the OTL EUFORIA evo will struggle with, both in terms of relative transient speed and dynamic range.
However, move over to dynamic driver headphones such as the Atrium and the outcome is a bit different. One that might actually come down to preferences more than anything.
With that solid-state rectifier, the Envy has a bit more of a push-pull character to its tonal quality with the Atrium. The bass is tauter and punchier but also slightly drier and brighter.
Whereas the EUFORIA evo is more of a classic tube bass tone meaning more voluptuous on the lows, slower decay, and slightly warmer in the timbre. It has more of an enveloping languid delivery compared to the snappier Envy bass performance.
You get a similar tonal response in the mids and highs with the Envy more forceful, offering more gusto and a slightly cleaner timbre in the process. It’s very strong for vocal solidity, and superb underlying PRaT also but it also lacks a little of that creamy smoothness of the EUFORIA evo mids and highs.
Hot take but I personally prefer the more saturated vocal quality of the Atrium/evo pairing over the energetic clarity of the Envy.
The Envy shows its superior class in terms of resolution and transient speed with dynamics to die for. However, its more neutral quality in the mids and highs can give the evo an edge for those looking for a smooth and richer timbral coloration.
Our Verdict
The Feliks Audio EUFORIA evo is an almost perfect riposte to the heady energy of the flagship Envy amplifier.
This is an elegant OTL amplifier tailor-made to give you a smooth embracing tone and one that works wonderfully well with headphones such as the ZMF Headphones Atrium and the Focal Utopia 2022. I could listen to these enjoyable combos for hours without fatigue.
Technically, it’s competitive also with impressive spaciousness and an ability to convey a source’s subtle tweaks into the general coloration and performance.
Efficient planars will work well but sound superb with a quality pre-amp in the system chain otherwise distortion can creep in on higher volumes. If you have more demanding planar headphones I do suggest looking at the likes of the Envy which has superior power and tweakability for those types of matchups.
Otherwise, this is a delicious-sounding and very impressive tube amplifier for high-impedance dynamic driver headphone owners.
Feliks Audio EUFORIA evo Specifications
- Impedance: 100k ohm
- Frequency response: 7 Hz – 80 Khz +/- 3 dB (300 ohm)
- Power output: 280mW
- Amplification level: 20dB
- THD: 0.4 % (300Ω, 20 mW)
- Optimal headphones impedance: 32 – 600 ohm including planar magnetics
- Headphones output: Jack 6.3mm
