• SPL Phonitor XE Headphone Amplifier Review

    May 26, 2019 Luckbad 1

    The Phonitor XE sounds like Maestro Dobel Diamante tequila. After I’ve had a few.

    The SPL Phonitor XE is Sound Performance Lab’s no-compromise statement headphone amplifier. It serves both the professional audio community as a reference headphone amplifier and audiophiles as a versatile, transparent solid state amp.


    Let’s quickly go over some of the features of the (feature-rich) Phonitor XE:

    • VOLTAiR 120V Rail Technology: This is proprietary SPL tech that is said to improve dynamic range, THD + Noise, and headroom.
    • Phonitor Matrix: By switching on the Matrix, you gain access to both the Crossfeed and Angle settings. These can simulate loudspeaker placement and adjust the stereo field.
    • Laterality: This knob gives you fine left/right control of the volume to each side of your headphones. Sometimes a recording isn’t properly balanced, or some of us have slightly worse hearing in one side.
    • Stereo/Mono/Laterality Switch: This lets you switch between stereo, mono, and the laterality mode mentioned above.
    • VU Meters w/ VU Level Switch: Gorgeous backlit VU meters that I tend to use to balance two sources when making comparisons. The switch allows you to attenuate the signal to the meters based on your input volume.
    • XLR Output (front/back): “Balanced” output. This gives you double the power of the SE output below. I believe it uses a dual power amp rather than being truly balanced from front to back.
    • 1/4″ Output (front/back): Single-ended output. Note: For the outputs, there is a switch to swap between front and rear options.
    • Remote Control Training: A super simple-to-use remote control setup lets you train any IR remote in seconds. I’ve tried small Bose and Apple remotes, and both worked like a charm.
    • Volume: An incredibly well-balanced volume knob that is motorized to turn when using the remote (Motorized ALPS “Big Blue“ Volume potentiometer). This volume pot does not exhibit any notable channel imbalance even at very low settings.
    • XLR & RCA Inputs: Both analog source inputs are on the rear of the unit. I cannot hear an audible difference between the two.
    • Digital Audio Inputs: Only if you have the optional Uber-DAC module. Since I don’t have the Uber-DAC module, I won’t cover it in this review.
    • Source Selector: Choose between XLR, RCA, and the digital inputs if you have the optional DAC module.
    • DIP Switches: Two on the bottom of the unit. Switch 1 increases the headphone output level to +22 dB. Switch 2 amplifies the RCA inputs from HiFi to to studio levels.

    You can find out more about all of the features both on the SPL website and by watching this (no audio–don’t crank the volume!) video.

    Build Quality

    I’ll briefly speak about the build quality of the Phonitor XE. In a word: outstanding. I’ve seen some uninformed criticism on the subject, talking about how it sounds hollow and doesn’t seem to warrant its size.

    Apart from SPL intentionally designing its Pro-Fi gear in stackable dimensions, if you take a look under the hood, you’ll notice a lot of components inside. Some components are rather large, like the custom toroidal transformer and front panel PCBs. And they need some room to breathe.

    The build quality, components, fit, and finish all appear to be top notch. It’s a strong combination of steel chassis, aluminum lid, and aluminum knobs. All of the parts are of the highest quality.

    The Phonitor XE comes in black, silver, or red to taste (only the front panel is a different color; the main chassis is black).

    How does the Phonitor XE sound?

    The SPL Phonitor XE is neutral, clean, resolving, and utterly transparent. It is reference grade. If you want to know what your source or headphones sound like, the Phonitor XE is a perfect choice. It’s clean, dynamic, distortion free, and highly revealing.

    Often if you hear those adjectives when describing an amplifier, you’d assume that I’d start bandying about terms like “analytical” or “cold.” That would then lead me toward words like “fatiguing.”

    The Phonitor XE is not those things. While it is exceedingly transparent, neutral, and exposes any of the strengths and weaknesses of your setup or recording, it’s almost… smooth?

    That’s the magic of the Phonitor XE. It is at once reference-neutral but easy to listen to. You can listen on it for hours fatigue free. I honestly have no idea how they pull this off. My guess it that it has something to do with the VOLTAiR technology.

    That magic could also be considered a weakness to some. While eminently listenable, the Phonitor XE is not the most engaging amplifier I’ve ever encountered for all headphones. It’s not aggressive, and it’s not romantic. It’s just… neutral. But there is a beauty in this neutrality that I’ve come to absolutely adore.

    I’ve used a number of headphones with the amp, including recent favorites like the MrSpeakers Ether 2 and ZMF Aeolus. My two primary headphones that I use with it, however, are the Sennheiser HD650 and Future Sonics MG5HX.

    You might wonder what the heck that second one is. It’s an in-ear monitor. And here, we come to a second component of the magic of the SPL Phonitor XE.

    It can power almost anything you throw at it. Its noise floor is incredibly low. I’ve never heard my IEMs perform at the level they do when using the Phonitor XE. It’s just freakin’ out of this world with them. Better even than the superlative IEM output of my RME ADI-2 DAC. And I can’t hear any noise whatsoever until I’m at about 95% of the volume dial (which would instantly cause permanent hearing damage if I were to listen at that level).

    Let me meander once more and speak of the merits of the SPL Phonitor XE. It accomplishes transparency in a way I’ve never quite experienced before. It is astonishingly powerful and dynamic, but it’s not aggressive. It possesses an effortless sense of power.

    There is no grain, no harshness, no sense of strain to the sound whatsoever. The smooth cleanliness is luxurious and invites me to turn up the volume beyond my normal listening level as music appears upon a perfectly black canvas.

    My normal listening volume on Sennheiser HD650s with balanced input and XLR output is right around 9 o’clock, but the Phonitor XE beguiles me to turn it up just a little bit more because I know that no fatigue will be induced.

    When I speak of fatigue, I talk about many different facets of both sound profile and technicalities. Distortion can cause fatigue even if it’s inaudible. Etched treble or sharpened delineation of the lines of music can do it as well. The top end of the Phonitor XE is at once smooth and airy. Spacious with sparkle but no glare or unwelcome bite.

    And let’s talk briefly of the bass capabilities of this amp, given that this is indeed Basshead.Club. The Phonitor XE is capable of delivering all of the bass you feed it. I can throw parametric EQ into the equation with a massive sub-bass boost, and the XE just smiles and delivers with absolute authority. The bass is tight and controlled and can slam beautifully.

    What else is worth talking about? Overall, I’ve had a preference for tube amplifiers for a number of years. This amp brought me around to properly enjoying a solid state amp for the first time in a very long while.

    One of the ways I measure the worth of an amp based on my own listening is to pay close attention to the sound of stringed instruments. The Phonitor XE has the best string bite I’ve heard from any solid state amplifier. That tends to be a big killer for me; either it’s too subdued, it’s the leading edge transients are too rounded, or the bite is artificially enhanced.

    Violins and cellos sound great on the XE. Acoustic guitar also has wonderful sparkle and timbre. The best tube amps still excel further in this area with just a touch more lasting shimmer, but I’ve never enjoyed a solid state amp as much as this for my tastes.

    Ignore the mediocre studio monitors and cheap interface. Those aren’t normally there!

    My Favorite Thing

    The SPL Phonitor XE is now my favorite piece of gear for evaluating what source gear sounds like (with my Sennheiser HD650s) or what headphones sound like (with my RME ADI-2 DAC). It paints an honest picture of your equipment and the music you’re listening to.

    My Least Favorite Thing

    While noted in the manual, you must not remove or insert headphones into the single-ended jack while music is playing. It’s possible for you to short the amp and have it go up in smoke. Be careful! I’d really have preferred something more robust in this case.


    Let’s mention system synergy momentarily. I’ve discovered the same combination that Ian Dunmore did in his review of the SPL Phonitor X: RME ADI-2 DAC → Phonitor XE → Sennheiser HD650

    The RME is fantastically neutral and resolving, just like the SPL Phonitor XE. This pairing is complementary to the point that you’re left with a reference-grade transparent combination and can hear exactly what a pair of headphones sounds like.

    The HD650 are my overall favorite headphones after many years in this hobby despite having owned many more expensive cans. The Phonitor XE helps elevate them beyond any other solid state pairing I’ve used in the past, helping to tighten up the bass and remove the last bit of veil that might be present.

    The other combination I’ve particularly enjoyed is: RME ADI-2 DAC → Phonitor XE → Future Sonics MG5HX

    That’s an IEM. From a monster amp. Overkill? I suspected so until I tried it. This combination is actually my favorite overall sound from any setup I’ve experienced, full stop. A 32ohm custom in-ear monitor targeted at musicians from a Pro-Fi setup in the RME → SPL. Go figure. It sounds darn near perfect to my ears.

    Phonitor Matrix

    I would dive deep into the Phonitor Matrix, but it’s been explained quite well by SPL themselves (and in reviews of the Phonitor X and other offerings). Subjectively, it’s the best implementation of crossfeed/angle/etc. that I’ve ever had the pleasure to use. I do find myself using it at times, particularly with IEMs.

    It exhibits minimal coloration or loss of impact and can be dialed in such that it sounds as if the recording was originally almost binaural. Note that the more extreme you go with the settings, the further you’ll get from neutral.

    I have, on more than one occasion, left the Phonitor Matrix switched on at the end of a listening session. Then, upon listening the next day, I had to make sure I didn’t accidentally leave my studio monitors on. It does an outstanding job of simulating the output of monitors placed in my room.

    I will also note one thing that’s not in the manual: the Phonitor Matrix is great for gaming. I’m a professional game designer and hardcore FPS player. In Overwatch, I’m getting better spacial cues with the Phonitor XE’s Matrix mode engaged than without. That was a pleasant surprise for me.

    Check out this video for info on the Phonitor Matrix.

    Bottom Line

    The SPL Phonitor XE is highly resolving, neutral, transparent, accurate, and has a dead black background. The magic of the Phonitor XE lies in its effortless delivery of power and uncolored presentation, all the while causing absolutely no listening fatigue.

    While not an inexpensive amplifier, I still feel it is an outstanding value for what you get. The DAC module might drive it even higher into value territory, but I have not had the chance to hear it.

    What is the highest recommendation one can give when reviewing a piece of gear? I’ll tell you: I decided to purchase the SPL Phonitor XE after an extended audition.

    SPL Phonitor XE Internal Pictures

    Leo Yeh of MY-HiEND has graciously allowed me to share these outstanding internal shots of the SPL Phonitor XE.

    MY-HiEND Audition Chamber: Internal Pictures of the SPL Phonitor XE

    Snagged from SPL’s video manual so we can see the Uber-DAC module.

    Categories: Amp, Gear, Reviews

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