THX Onyx DAC/Headphone Amp Review

Posted on 7th April, 2021

THX Onyx DAC/Headphone Amp Review

Jay Garrett samples a dynamic new dongle with a very famous name…


Onyx Portable DAC/Amp


THX Onyx review

As ever more headphone wearers discover the benefits of adding external DAC/amplifiers to their portable hi-fi systems, so the number of companies catering for them increases. Some offerings come from established brands such as AudioQuest and the EarMen branch of Auris Audio, while others such as Zorloo are relative unknowns. Then there is THX. Many will know the name as a standard for digital cinema sound founded by George Lucas, not as a consumer hardware manufacturer – until now, that is.


The THX Onyx is an ultra-portable DAC/headphone amplifier in much the same way as the Zorloo Ztella, as its USB-C and headphone port terminations are captively hardwired, unlike the EarMen Sparrow's pebble-smooth module which can detach from all cabling. However, where most cables are braided, THX has gone with thick yet supple silicone sheathing. The business end is a CNC-machined metal body, topped-off by a 3D THX logo. Joining this is a row of LEDs that light up blue for 44.1 or 48kHz PCM, yellow for 48kHz PCM and above, red for DSD and magenta to indicate Master Quality Authenticated audio.

THX Onyx review

Like its rival EarMen Sparrow, the Onyx sports the highly regarded ESS ES9281PRO flagship DAC – but the latter differs with its implementation of THX AAA-78, the highest-powered mobile THX Achromatic Audio Amplifier (THX AAA) specification, we are so informed. The Onyx is said to produce the same power as a desktop THX AAA DAC/amp. This patented technology claims the highest fidelity audio with seriously low levels of noise and distortion. It’s said to produce 180mW per channel with less than 0.1% THD, so should happily drive all headphones regardless of impedance.

The headphone port supports microphones on a TRRS connector, so if your cans have an inline microphone or – more to the point – you’re using a gaming headset, you can plug it straight into the Onyx and still use your mic as usual while benefitting from improved sonics via the DAC/amp. It comes bundled with a USB-A adapter should your PC, MAC or laptop not sport USB-C.

THX Onyx review

Another neat feature is that the area underneath the THX logo is magnetic, enabling you to use the resulting loop as a bit of a cable tidy.


The Onyx is plug-and-play, which is a big win as far as this reviewer is concerned. I was expecting to fiddle around with the settings when using my Astro A40 TR headset, but no need. That meant I could have a break from thrashing around tracks in Project Cars or getting picked-off in Warzone, and set TIDAL playing to hear unfolded MQA tunes without swapping amps or headphones. Hook up some better headphones though – like my reference Ultrasone Edition 15 Veritas, Oppo PM-1 or Focal Clear Mg – and the Onyx steps up a gear to produce clear, well-defined music with no sense of strain.

THX Onyx review

For example, Demi Lovato's inflexions came over loud and proud as I played Anyone from TIDAL in MQA via USB Audio Player PRO on my Huawei P30 Pro. The room reverb on the vocals was as genuine as the emotion in her voice. Because of the Onyx's gaming and movie heritage, I was expecting over-hyped bass relying on stacks of rumbling sub-sonics, but it didn’t happen. Beyonce's Drunk In Love Remix delivered a detailed bottom end with a presence more akin to a well-honed personal security detail than town-end bouncers.

This was good news when playing classics such as Harold The Barrel by Genesis with the dongle plugged into my PC. This three-minute track came through evenly balanced with a lovely shimmer to the hi-hats, and the piano had a live leading edge with plenty of midband clarity. Down in the low frequencies, bass guitar and kick drum had plenty of room to manoeuvre without clashing. I could easily pick out the various strands of this track and focus in on them, be it the melodic high notes of the bass or the harmonised vocals.

THX Onyx review

As a Roon fan, it was great to see the Onyx pop-up on the list of available audio endpoints on this practically essential piece of streaming software. A few rounds of gaming proved it was no slouch in this arena either. Gunshots resonated through my headset with unnerving realism while the dialogue between team members was crystal clear. My only reservation using the Onyx as a gaming DAC/amp with my PC rig is that level adjustment between voice and game, as well as overall volume, is easier using the dials on my Astro amp. That said, for portable gaming, it certainly upskills the laptop, tablet or phone you're using.


Priced at less than the EarMen Sparrow and DragonFly Cobalt and just a few quid more than the DragonFly Red, the THX Onyx represents great value for money. Sound is crisp and open, and it has plenty of poke when needed. As such, if you’re on the lookout for a versatile DAC/amp dongle, catch it if you can.


Jay Garrett's avatar

Jay Garrett

StereoNET UK’s Editor and Bass playing gadget junkie. He’s captained the good ship GadgetyNews for over a decade, making low jargon high tech a very handy thing. His passion for gadgets and Hi-Fi is second only to being a touring musician.

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Posted in: Headphones DACs Applause Awards 2021 Headphones Headphone Amps
Tags: mqa  roon  thx 


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