Mytek Liberty THX AAA Headphone Amplifier Review

The Mytek Liberty THX AAA Headphone Amplifier was a pleasant surprise. I was initially suspicious of the THX name on the front. But now that I know more and have heard more, those suspicions were misplaced. This is a very, very good headphone amplifier.

These days there are almost as many headphone amplifiers as there are headphones with lots of choices in both price and design philosophy. The Mytek Liberty THX AAA headphone amplifier is definitely a premium product with the goal of providing a high-power headphone amp capable of driving almost any dynamic (meaning non-electrostatic) headphone with the lowest possible distortion. This amp is not a minimalist, ultra-simple amp, nor does it use tubes. It does offer some of the cleanest, clearest lowest coloration sound reproduction I’ve heard through my headphones. If the idea of a “wire with gain” sounds like a good idea to you the Liberty THX AAA amplifier might be just the ticket you’re looking for. On top of that, it has a plethora of inputs and outputs supporting virtually any dynamic headphone balanced or unbalanced.

The Mytek THX AAA headphone amp’s name reveals the main detail of its design. Rather than design the whole amp from scratch, Mytek has licensed the THX AAA 888 “reference design” from THX. The THX AAA 888 isn’t an integrated circuit chip or physical module. It’s a circuit design that THX has developed. THX then licenses that intellectual property to customers to use in their products. The THX Achromatic Audio Amplifier (AAA) series are seven reference designs varying in application from mobile devices like wireless headphones (the THXAAA0) up to desktop amps.

The Mytek amp uses the top-of-the-line THXAAA-888. This is the “no compromises” design from THX, with super low distortion and signal-to-noise, and high-power output. The Mytek THX AAA amp puts out up to 6W into a 16-ohm load if needed, which is exceptional for a headphone amp. Power output into higher impedances is lower as expected, with 3.9W into 32 ohms and 0.465W into 300 ohms.

The total harmonic distortion is documented at a super low -150 dB. Into a 300-ohm load and -140 dB into a 16-ohm load, with an a-weighted SNR of 137 dB. The cost for all this performance is an idle power consumption of almost 3W. This is straight off the THX data sheet for the AAA product line. Since the THX amp is just a design, it’s up to Mytek to implement it without screwing it up. The Liberty amp has a super oversized 60W toroidal transformer linear power supply with dual mono regulators and top-of-the-line passive components.

The connectors, circuit boards, the volume pot, and the enclosure are all top quality. Not ridiculous audiophile hocus-pocus level, but top quality from an electrical engineering point of view. One interesting thing I noticed when I opened the lid is that while the THX AAA amp sections are clearly labeled on the circuit board, the main IC chips for the dual mono amp modules have had their tops sanded off or laser etched to remove all the markings. So, I can’t tell you what chips are used. This is almost certainly a THX requirement to prevent people from so easily reverse-engineering the circuit design.

Operating the Liberty THX AAA is pretty straightforward. Except you have to read the front panel fine print to turn it on. There’s no separate power switch. You press and hold the input select button for 3 seconds to turn the amp on. That input select switch picks from the three single-ended RCA inputs or the balanced XLR inputs that use Neutrik XLR combo jacks which allow both XLR and ¼” stereo receptacle in the center. In recording studios, ¼” stereo plugs and jacks are used for balanced audio connections often.

Another feature that could make the Liberty THX AAA useful in the studio is the ability to sum all four inputs together. Pushing the input button cycles between the four inputs individually plus all four being active at once. The next button allows adjustment of the amplifier gain, with +6 dB, 0 dB (labeled “normal”), -6 dB, and -12 dB settings. This allows you to tune the gain of the amp such that you can use the volume knob in the middle of its range with pretty much any headphones.

The final button controls the crossfeed filters. Crossfeed mixes some of the right signal into the left channel and vice versa, usually through a time delay and/or equalization filter to give more of a loudspeaker-like sound and soundstage to headphone listening. On the Liberty amp, there are 5 settings: two filter styles with normal and high levels of crossfeed, and off. The button also selects mono mode if you should desire. These crossfeed circuits are not documented. You just pick the setting you like the best. This brings up my one complaint about the Liberty THX AAA amplifier: the manual. None of the controls are documented in the manual at all. There is a video on the Mytek website where Mytek’s designer Michal Jurewicz goes over all the controls. But I really wish they would make the effort to write it down in the manual. It wouldn’t be that much work.

I used the Liberty THX AAA on my desk at work, fed by a Chord Mojo connected to a Windows PC using the USB input. The source was either Jriver Media Center or the Qobuz desktop application. I used my trusty Sennheiser HD-600 open-back headphones and also tried my Hifiman RE-800 IEMs, which I usually use with the Mojo on portable duty. Both these headphones are easy loads to drive. The HD600s are 300 Ohms, and the RE800s are 60 Ohms. I don’t own any balanced input headphones or cables, so I didn’t try either of the balanced outputs.

To break the amp in, I set it at a moderate listening level with headphones connected and let music play over a full weekend. I settled on the –6dB gain setting, which allowed me to use the volume potentiometer in the middle of its range. I settled on the NORM1 crossfeed filter as my favorite when using Qobuz, and set it to off when using Jriver Media Center, where I used the Jriver crossfeed plugin. This is totally a personal preference. I’ve been a fan of crossfeed since back when Headroom was the only game in town for headphone amps and have continued to use it when available. But of course, many prefer no crossfeed at all.

Unlike at home, I did most of my listening at work with Qobuz streaming. Qobuz offers 16-bit 44.1 kHz digital at a minimum, streams up to 24-bit 192 kHz when available, and does not require any special hardware like Tidal with MQA. I’m a big fan. The sound quality is excellent, and I’m reasonably impressed with their music catalog.

My first impression is that the music sounded like it was carved from a solid block of granite. It had the solidity, presence, and weight of a big 1970’s Mercedes car door closing. Like a bank vault door. Not that the sound was heavy or ponderous in any way. Just a clear sound of ultimate control, precision, and solidity without one hair out of place. I also quickly noticed that the amp had no “sound”. It was exceptionally neutral. So, as I listened to track after track, I struggled to come up with words to describe the “sound”. I couldn’t come up with any because there wasn’t one. It reminded me of the amplifier equivalent of good single-driver IEMs like my RE800s. It’s like plugging the interconnects directly into your brain, bypassing the headphones.

The Mytek Liberty THX AAA is not cheap at $1,495. But you get what you pay for. It is exceptionally transparent, can drive pretty much any headphone, is packed full of capabilities, and has exceptional technical performance.

The Mytek Liberty THX AAA is a very good headphone amp. It’s one of the most transparent, character-free pieces of analog electronics I’ve ever heard. It has stunning specifications. Even with my relatively easy-to-drive headphones, it added quite a lot to what I heard. Or didn’t hear more specifically. Some people like audio equipment with “character”. If you’re one of those people, the Mytek Liberty THX AAA isn’t for you. But if you want “a straight wire with gain”, and especially if you have hard-to-drive headphones, this amp is definitely for you.