Pure Tube Excellence | Feliks Audio Euphoria EVO Review

Pure Tube Excellence | Feliks Audio Euphoria EVO Review

Feliks Audio Euforia EVO is the long-awaited update to the original Euforia, which was released almost six years ago. Euforia EVO doesn’t change too much about the original, instead it provides some small changes to the design and improvements to the components under the hood. With Feliks Audio’s advancements in vacuum tube technology, can Euforia EVO provide the best in accuracy and clarity along with the smooth character of classic tube amps?

Build and Design

With its aluminum chassis and coke bottle tubes, Euforia EVO is quite the looker. Its relatively small footprint also means that it won’t take over your desk the way that some other high end tube amps might. The tube complement is two 6SN7 driver tubes and two 6N13S power tubes. Feliks Audio provides a pair of Psvane Audio CV-181 Mk2 tubes for the front, and a matched pair of unlabeled NOS 6N13S for the power section. Note that when you’re installing the included tubes, Feliks Audio provides the preferred position for the matched pairs for optimum performance based on their measurements.

Feliks Audio Euforia Review

The device’s only input is RCA, but for output you have RCA preamp and 6.3mm or XLR headphone output. In terms of device controls, you only have a power switch, a volume knob, and a crossfeed on/off switch. The volume knob is big and smooth, but I found the markings to be a little bit confusing

Features and Performance

While you don’t get a lot in terms of features, Euphoria EVO’s crossfeed execution is definitely worth talking about. The core idea behind it is that rather than simply blending a percentage of the left channel into right and the right channel into left, it blends more of the low end frequencies and tapers off into the midrange and treble. This creates the effect of adding cohesion to recordings with a large degree of channel separation – particularly many classic rock albums of the 60s and 70s. As an example, on many of the tracks on The Beatles White Album the bass guitar is panned to the right along with Paul McCartney’s voice, creating an unbalanced feeling of too much bass on the right side and too little on the left. Euphoria EVO’s crossfeed centers the bass frequencies, but leaves the rest alone, providing a more natural sounding output while leaving Sir McCartney himself – and the higher frequencies of more articulated bass playing – in the same place in the image.

With more modern recordings I found it to increase the volume of bass, but sometimes add a small degree of congestion. When the mix already has the bass primarily pumping down the center channel, it seems like the crossfeed can actually end up adding more bass as well, so I preferred to turn it on for older recordings and off for most newer tracks.

Feliks Audio Euforia Review

The wattage is listed at 280mw and it provides ample power for most headphones as tube amps typically provide much more practical output power per watt than their solid state equivalents. The basic operation of Euforia EVO is pretty simple, and while it doesn’t have a ton of switches or knobs, the ability to change tubes gives you a pretty massive amount of power to customize your sound. All around the device has an elegant simplicity that’s easy to use while hiding surprising power when you look a little closer.

IEMs performed quite well in my testing, with the Noble Viking Ragnar, Kinera Nanna 2.0, and Vision Ears Phonix. Euforia EVO delivered excellent performance across the board. You get a good amount of output control, with no major jumps in the volume, and a low noise floor. If you’re looking at this as an all-around desktop solution for your collection, it really can provide excellent performance from a wide range of planar magnetic and high impedance dynamic driver headphones to sensitive IEMs.


Euforia EVO is designed with a simple goal: creating an OTL tube headphone amp with a highly linear output. While many amps that aim for a highly accurate, reference delivery end up sounding dry or analytical, Euforia EVO delivers a sound which is clean and transparent, but with just the right amount of silky smooth character to maintain the musicality.

Feliks Audio Euforia Review

Its bass response is characterized by a solid support of the low bass frequencies without any sort of emphasis or bass added. Headphones like the Sennheiser HD800S or Audeze MM-500, with slightly rolled off subbass, demonstrate good slam and dynamics in the bass with Euforia EVO. At the same time, headphones with more emphasized low end, like the Dan Clark Expanse, don’t have any sense of added bass or bloat. The bass texture is excellent, and Euforia EVO provides loads of detail and character for bass instruments.

The midrange is rich and detailed with a natural timbre and good weight to vocals and instruments. In the same way that the bass supported bass-lite headphones without actually adding any bass, the mids feel like they fill out recessions in the midrange nicely, but don’t emphasize or push the mids forward. Treble is accurate and well extended, with just the smallest hint of smoothness in the sharpest peaks in fatiguing regions, but overall clear and airy.

Euforia EVO’s presentation of the stereo image is incredible, delivering a wide, three dimensional soundstage and lifelike, holographic imaging. There’s a clear sense of height, width and depth to the space and excellent placement of instruments and both from left to right and from front to back. Euforia EVO has a habit of filling in the missing pieces in a headphone, with one example being the HIFIMAN Arya, which gained a improved sense of weight to the imaging and had its already excellent soundstage enhanced. Vocals in particular have a highly personal, intimate feeling, and frequently deliver chills (the good kind) on an emotional high note.

Feliks Audio Euforia Review

The character of Euforia EVO’s output is very much determined by the rest of your signal chain, and your DAC choice will make a big difference. Using the Astell&Kern ACRO CA1000 desktop DAP resulted in a somewhat smoother overall tone and a more moderately sized soundstage. With a Chord Qutest, there was a greater sense of resolution and crisp clear highs with a wider soundstage and more vivid imaging. The Weiss DAC502 provided an absolutely transcendent experience with both incredible levels of detail, immersive imaging, and nearly flawless musical delivery.

The Bottom Line

Euforia EVO delivers excellent performance that’s coupled with an elegant simplicity. While tube amps can seem intimidating – and adding in a fancy concept like the “output transformerless” design can add to that – but EVO’s plug and play nature and single volume knob operation makes it highly accessible. While the elegance and accessibility is great, what’s most important is the sound, and Euforia EVO is, without a doubt, one of the best sounding headphone amps we’ve ever heard.