Review: The THX Onyx Portable DAC’s Got Game

Portable dongle DACs are experiencing a renaissance for the first time.

I recently reviewed three dongle DACs and compared them to two others. In ascending price order, the players included the iBasso DC03 ($69), Helm Audio BOLT ($99.99), AudioQuest DragonFly Red ($199.95), AudioQuest DragonFly Cobalt ($299.95), and the Clarus CODA DAC ($300).

When I received an email invite to review yet another, I said yes pretty much immediately. You may think I have a thing for portable dongle DACs which is kinda funny because I rarely go anywhere, especially in our recent infectious times. So portability is not a requirement for my listening habits, yet here I am, ready and willing to write about a 6th portable dongle DAC.

One of the things I like about portable DACs is they are simple. Another thing that I find attractive is price — simple, portable dongle DACs are relatively inexpensive in the grand scheme of hifi things.

The THX Onyx Portable DAC offers a USB-C input which sits at the end of a flexible rubber cable that is hard-wired to the CNC-machined black metal chassis which houses the Onyx’s guts. The output is a sole 3.5mm analog jack for driving headphones or hifi’s. An ESS ES9281PRO is responsible for digital to analog conversion, which is capable of passing PCM resolutions up to 32-bit/384kHz and DSD to DSD128, while also covering the final and full unfold of MQA-encoded music. The company notes that all incoming PCM and MQA data, regardless of religion, is upsampled to 705.6/768kHz.

image credit: THX

The amplifier inside is the THX designed and built THX Achromatic Audio Amplifier (THX AAA-78). THX states that the AAA-78 ensures the ultimate no-compromise headphone audio experience by delivering the world’s highest fidelity audio with infinitesimally low levels of noise, distortion and power consumption through the use of patented feed-forward error correction topology that nulls conventional distortion mechanisms. We’ll just have to hear about that! While the Onyx does not sport the THX Certification seal, the company assures us it does meet all of the rigorous THX Certification standards for mobile DAC amps.

The Onyx’s slender elongated rectangular body bears the company name in slightly raised shiny silver letters and three multi-colored LEDs that indicate the quality of the incoming data (Standard = 44.1 /48kHz, High Resolution = >48kHz, DSD, and MQA). The underside of the chassis on the input side is magnetized so it can hold the UBC-C up close and personal, like so:

Overall, I’m a fan of the look and feel of the Onyx and as an iPhone owner, I appreciate the inclusion of a USB-C to USB-A adapter. With it, I can connect the Onyx to an Apple Camera Connection Kit (CCK) which in turn plugs into the iPhone so I can get digital audio out untouched by Apple’s ideas about digital.

I put the THX Onyx Portable DAC through its paces in my desktop system, connected to one of the iMac’s USB-C outputs, and with the help of a 3.5mm to RCA Adapter and a pair of AQ Red River interconnects, the Onyx fed its analog output to a pair of ADAM A3X powered speakers. The Onyx also spent some time in my main system as well as driving a pair of AQ NightOwl headphones with my iPhone as source.

The THX Onyx Has Got Game

The obvious Onyx comparison among the portable dongle DACs in Barn is to the similarly priced AudioQuest DragonFly Red. I’ve owned and used the Red for years, and enjoy its well balanced meaty sound. While it does not offer the last word in resolution, I find it to be a very enjoyable DAC to listen to over time.

On my desktop, in my main hifi, and through the NightOwl headphones, the Onyx proved to be more than the DragonFly Red’s equal. The Onyx presents music with greater resolution coupled with greater clarity. While never sounding overly analytical, the Onyx did a better job of pulling music’s details, tones, and textures from digital music as compared to the DragonFly Red. This made Maggie Rogers, from the super lovely Notes from the Archive: Recordings 2011-2016, sound more present, more fully formed, while the supporting cast were better defined and richer sounding all around.

These differences, which I’m comfortable calling improvements even though some people may prefer the DragonFly Red’s more laid back sound, were easy to hear in each of the systems I used for this review. Even leashed to the review (for Rotel RA-1592MKII integrated amplifier driving the easy to drive DeVore Fidelity O/96, the Onyx delivered music that was easy on the ears yet finely nuanced and fairly full bodied. I say fairly full bodied because the Onyx is no match for a DAC like the Denafrips ARES II when it comes to ultimate body, tone, and texture but no one, in their right mind, would expect a dongle DAC to compete with even a half-sized non-portable DAC costing about 4x the price of the Onyx in a system costing north of $15k. System building is, in part, a question of balance which often also applies to component price.

The little Onyx drove the ADAM A3X like a champ and I could easily live with this combination as it offered super resolution, captivating clarity, rich tone, and some very nicely defined bass. Playing “Scratchcard Lanyard” from Dry Cleaning’s New Long Leg, which I cannot recommend highly enough, drove that bass response home with those opening bass lines sounding big, round, fit, elastic, and fun. The Onyx/ADAM combination also laid this good-sounding record out in a very tightly defined space, with each player taking up a solid position within the sound image. Nice.

blame Apple for the roundabout

If I put the Onyx into the company of all the players in my Dongle DAC Survey, I’d say it still fares very well. The AQ Cobalt does offer more ease while equaling the Onyx in terms of resolution, so I found the Cobalt offered a slightly more cohesive and engaging sense of music’s energy, as compared to the Onyx. These traits were most noticeable when listening through the NightOwl headphones, where things like the room are taken out of the picture. Here, in headphone mode, the Cobalt sounded silkier and smoother than the Onyx but we’re not talking about a dramatic difference. Even going back and forth between the Cobalt and the Onyx, I remained impressed with the THX.

Rounding Up

If you have around $200 to spend on a portable dongle DAC, your money is very well spent on the THX Onyx, no ifs, ands, or buts. Its strengths are centered around presenting music that’s rich, full, and finely nuanced, qualities that I find lead down the path of more listening and more enjoyment. Bravo!

THX Onyx Portable DAC
: $199.99


Input Type: USB-C or USB (via included adapter)
Output Type: 3.5 mm analog jack
Output Impedance: 0.25 Ohms
Dynamic Range: 118 dB
Quality (THD+N, 1kHz): -110 dB
Output Power (Per ch, 22 Ω, <1% THD+N): 180 mW
MQA Playback: Yes
Headset Mic Support: Yes (Use with iOS products is for media consumption only, no call or mic functionality.)
USB & DAC Config: ESS ES9281PRO
AMP Config: THX AAA-78
Compatible Platforms: Android, iOS, Windows 10, and Mac (USB-C to Lightning adapter not included)
Accessories: USB-A Male to USB-C Female Adapter

Company Website: THX