THX Onyx review: Setting the bar for portable DAC amps

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Techaeris Rated 9.5/10

We’ve reviewed numerous amplifiers over the years. A few of these are portable, others not so much. Some of the newer DAC amplifiers come with THX technology for superior audio. Typically, these are third-party devices, but THX has just released its own portable DAC amp (and first consumer device): the THX Onyx.

Estimated reading time: 10 minutes

The THX Onyx includes THX AAA (Achromatic Audio Amplifier) technology, an ESS Pro DAC chip, and has MQA (Master Quality Authenticated) support, all in a neat, tidy package. Combining these in one device was because THX wanted to create a “best-in-class” portable DAC amplifier that ensures lossless, pure sound so listeners can hear content the way the artist intended.

“THX was founded on the principle that quality matters. We’ve remained dedicated for more than 35 years to innovation that ensures whatever an artist creates can be enjoyed by the audience in the manner intended. Consumers looking for the best audio experience over wired headphones may have found the quality is compromised, so we’re stepping up with a flexible, high-quality, and affordable solution with the launch of our first consumer product, THX Onyx.”

Jason Fiber, chief operating officer, THX Ltd

We were fortunate enough to receive an advanced unit. Our THX Onyx review looks at a portable DAC amplifier with MQA support, boosting your headphones’ audio quality regardless of where or how you listen to music. Read on to find out why it won a Top Pick of 2021 Award here at Techaeris.


The THX Onyx Portable DAC Headphone Amplifier we reviewed has the following features and specifications:

  • THX Achromatic Audio Amplifier (THX AAA™)-the first mobile device with the hi-fi THX AAA-78 for ultra-low distortion and noise, with 5x more output power than other similar USB DAC/Amps
  • Master Quality Authenticated (MQA) renderer to reproduce digital master recordings
  • ESS ES9281PRO DAC for flagship studio sound quality
  • Cross-platform compatibility for convenient plug-and-play
  • Magnetic cable management to keep headphone wires neat and tangle-free
  • PLUG and PLAY: works with PC, Mac, Android, and iOS, plugs into any USB-C or USB port, and requires no drivers or installation. PC is for Windows 10 only with Windows OS. iOS requires the slim Apple Lightning to USB Camera Adapter, sold separately.
Input typeUSB Type-C/USB-A
Output type3.5mm analog jack
Headphone impedance range22-1000 Ohms
Sound quality (THD+N, 1kHz)-110 dB
Dynamic range118 dB
Output impedance0.2 Ohms
Output power (per ch, 22 Ω, <1% THD)180 mW
MQA playbackYes
Headset mic supportYes (Mac, PC, Android), no mic on iPhone/iPad
Microphone noise-98 dB
USB & DAC config ESS ES9281PRO
AMP configTHX AAA-78
Compatible platformsAndroid, iOS, Windows 10, and Mac (Lightning to USB-C Camera Adapter (slim) not included)
AccessoriesUSB-A male to USB Type-C female adapter
Dimensions7.2 x 14 x 210mm (0.28 x .55 x 8.26″)

What’s in the box

  • THX Onyx
  • Male USB-A to Female USB-C adapter
  • Important product information guide
What's included with the THX Onyx Portable DAC Headphone Amplifier
What’s included with the THX Onyx Portable DAC Headphone Amplifier.


Portable amplifiers come in all shapes and sizes. The THX Onyx is by far one of the smallest, cleanest, and sleekest looking ones I’ve seen to date. With its black CNC-machined aluminum finish on the main unit and the USB-C connector, the silver bevelled accents tie in nicely with the raised THX logo. The amplifier portion is just under 2 1/2 inches in length, just over 1/2-inch wide, and 1/4-inch in height. Besides the THX logo on the top, there are three LED lights. A 3.5mm headphone/microphone jack is on the end.

The amp connects to the USB-C connector by way of a 5-inch soft rubber-like coated cable. The cable tapers out at each end, adding to the slick look. The USB-C end measures about 5/8-inch in length, 3/8-inch in width, and 1/4-inch in height.

I don’t have any issues with the design at all, it is compact and sleek looking. Plus, it doesn’t need to be charged or plugged in like some other portable amps do. While this is the only version currently, it’d be nice to see THX or another company come out with a similar design for USB-C and/or USB-A headphones.

The THX Onyx Portable DAC Headphone Amplifier
The THX Onyx Portable DAC Headphone Amplifier.

Ease of Use

The THX Onyx Portable DAC Headphone Amplifier is, for the most part, plug and play. Plug the USB-C end into a USB-C port on your computer, smartphone, or tablet, plug your 3.5mm TRS or TRRS headphone jack into the other, and you’re pretty much good to go. If you don’t have a USB-C port, you can use the USB-A to USB-C adapter and use a USB-A port on your computer. If you have an iOS device, you will have to pick up the slim Apple Lightning to USB Camera Adapter.

The LEDs on the Onyx will flash blue one at a time, then magenta together to indicate the device is active and ready to go. When there is no headset connected, the middle LED will glow blue, then the outer two, before repeating until a headset is connected. This indicates that the device is in power save mode and not drawing as much power.

In playback mode, the three LEDs light up, indicating the sample rate of the audio being played:

  • Blue: 44.1 or 48 kHz PCM, Standard Quality
  • Yellow: >48 kHz PCM, High Resolution (Better Quality)
  • Red: DSD, Direct Stream Digital (Better Quality)
  • Magenta: MQA Render, Master Quality Authenticated (Best Quality)

Windows 10

Unfortunately, on my first go, I was only able to get standard quality on the laptop and high-resolution quality on Android. On Windows 10, it is a pretty easy fix and THX will have a number of user guides available for users. In Windows 10, you have to go into Control Panel > Sound > Playback and set THX Onyx as a 24- or 32-bit device at 176.4 or higher bitrate. Next, launch Tidal with a Tidal HiFi account (not Premium). Click on the … on the upper left of the app, then Settings > Streaming > set Streaming Audio Quality to Master. Change the Sound Output Device to THX Onyx. Then in the lower right of the app, click on devices, highlight THX Onyx USB Amplifier, and click More Settings. Make sure Use Exclusive Mode is enabled and disable both Force Volume and Passthrough MQA. After you’ve done this, you should see three magenta lights on playback.

The USB-C connector on the THX Onyx Portable DAC Headphone Amplifier
The USB-C connector on the THX Onyx Portable DAC Headphone Amplifier.


For the MQA/TIDAL playback/rendering over Android devices, there is a known issue with MQA. They have assured THX that a fix in the works is coming, so this issue should be resolved soon. However, you can purchase and download the UAPP (USB Audio Player Pro) app from the Google Play Store, configure it, and you should be good to go. Once we’ve test that out, I’ll be updating this section with tips on how to configure it.

Sound Quality

I hate to admit it, but the THX Onyx might turn me into an audio snob. I’m not new to DACs or portable amplifiers, welcoming the boost in audio volume and quality, but the Onyx takes that to a new level with the THX AAA-78, ESS ES9281PRO DAC, and MQA renderer. Before I continue, I will note that the THX Onyx isn’t THX-certified for obvious reasons. That reason being you can’t really certify your own product. That being said, this portable DAC meets the same high standard as any rigorously tested THX Certified product and, if it were a third-party device, would pass the THX certification process.

During testing, I used the THX Onyx with a Pixel 5, a Razer Blade 13, the Razer Blackshark v2 headset, and the Creative Aurvana Trio earbuds. You could also use it with desktop speakers that use a 3.5mm connector, but I didn’t have a set handy to try out.

To test the differences in audio quality, I used the Blackshark V2 without its USB amplifier. To connect to the Pixel 5, I used the Google Pixel USB Type-C to 3.5mm adapter and for the Razer Blade 13, the 3.5mm audio jack. I then used both devices, and both sets of headphones with the THX Onyx connected to USB Type-C ports. As for source material, I did test movies, games, and music — the latter with a TIDAL HiFi account to access the Master (MQA) quality for available tracks.

As mentioned above, the THX Onyx has a series of LEDs that change from blue, to yellow, to red, to magenta, depending on the source audio quality. Initially,y, the Razer Blade 13 showed blue (or standard 44.1 or 48 kHz PCM) quality, while the Pixel 5 showed yellow (or higher > 48 kHz PCM) quality. In both cases, there was a noticeable improvement on both the Blackshark V2 headset and the Aurvana Trio earbuds. My review unit of the Audeze LCD-1 just arrived today and I’m looking forward to testing those out as well.

One of the three LEDs lit up on the THX Onyx Portable DAC Headphone Amplifier
One of the three LEDs lit up on the THX Onyx Portable DAC Headphone Amplifier.

After properly configuring Windows 10 and TIDAL to output Master (MQA) quality tracks, the Onyx LEDs turned magenta, showing the music I was listening to was of the highest quality. I spent the next hour toggling between Normal and Master quality in TIDAL on the THX Onyx Demo Playlist and being pleasantly amazed at the differences in sound quality. This playlist includes Mozart, Steely Dan, the Eagles, Pink Floyd, Lady Gaga, Nirvana, Beyoncé, and more. In other words, a nice rounded playlist. Not only was the audio boosted in volume, but the range and level of detail in each track I listened to was noticeable. And I definitely noticed new layers in some tracks that I hadn’t noticed before. Even at full volume, which I wouldn’t suggest, the audio was crystal clear and with no signs of distortion.

I also watched a couple of videos and played a few rounds of Heroes of the Storm on the laptop and Call of Duty: Mobile on a smartphone. Again, even though I was only receiving standard or higher quality audio, it made enough of a difference in both cases compared to listening without the THX Onyx connected. Switching over to THX’s suggestions, I fired up “Lord of the Rings | Middle Earth Music & Ambience, 3 Hours” on YouTube. Even though it played at the >48 kHz PCM setting, it sounded excellent and full. Watching the final battle scene in Avengers: Endgame was a treat, as was the beginning of Soul with the high-resolution audio and 180mW output from the Onyx.

While we weren’t able to test MQA/Master quality on Android quite yet (we’re waiting for a copy of UAPP to test with), the sound quality was better than without, and I have no doubt it will be even better with MQA rendering enabled properly.


With an MSRP of US$199.99, the THX Onyx isn’t exactly cheap. While I’m still not sold on spending as much or more on a portable DAC amplifier as you do your headphones, the audio quality improvement is definitely there. Given the Onyx also has an MQA renderer, it does offer more value than some other portable amps currently on the market. Plus, it’s small, sleek, and has a solid design and build quality.

The THX Onyx can be purchased from or

Chart comparing THX Onyx to other portable DAC amplifiers (provided by THX)
THX Onyx compared to other portable DAC amplifiers (provided by THX).


If you’re looking to truly enjoy your audio, whether it be music, movies, or games, the THX Onyx Portable DAC Headphone Amplifier will allow you to do just that, especially if you have access to MQA recordings like TIDAL’s Masters. This was an easy Top Pick here at Techaeris for 2021.

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