• Taz

THX Onyx Portable DAC - Upgrade Your iPhone's Sound

As iPhone users will be aware, there's not much 'audiophile-ness' about Apple's phones. They are designed with ease of use and as little tinkering about with as possible. I have bought into the Apple ecosystem for other elements of my life.

For years I've used the basic Lightning to 3.5mm audio jack adapter to play music from my iPhone. It works, and is fine for travel and walking around.

With headphones attached it's a neat solution and doesn't add too much bulk to the iPhone.

However, there's that constant nagging feeling in me that the music should sound better - particularly as I have a large and growing library of CD-quality and Hi-Res files that I've purchased over the years.

There are now a number of portable USB DACs with a very compact form factor as their main feature in recent months. I do have an iFi hip dac too but it's a bit unwieldy for me when attached to my iPhone, even though it is relatively small.

Lately there have been a slew of portable DACs released with the ESS ES9281PRO DAC chipset. These are mostly hovering around the 100GBP price point. One stood out to me: the THX Onyx, mainly because it's twice as expensive as its rivals so I wanted to see what I would get for such an increase in price.

For the doubling in price, you do get to listen to music from the THX Achromatic Audio Amplifier (THX AAA™), which sounds interesting, right? Over and above that you do get MQA decoding if you listen to Masters songs on TIDAL, and you do get a slim and compact form factor with plug and play convenience.

I purchased mine direct from Razer:


I paid 199.99GBP, which includes postage and packing. Looking at the tracking information, Razer shipped my THX Onyx very quickly indeed. It was literally on the way within 24 hours of placing the order. It was shipped from Hong Kong. 24 hours after that it arrived in the United Kingdom. How's that for a speedy dispatch? 48 hours from order to arriving in the UK! The carrier was DHL and full tracking information was provided. Comms from Razer was excellent.

After it arrived in the UK it did sit at East Midlands Airport for several days. This was not due to any customs issues, but the lack of availability of a slot to get it to where I live (London). From East Midlands Airport it took 6 days to get delivered.

So, let's take a look at the THX Onyx in a little more detail.


The THX Onyx arrives in a nice, compact cardboard case that is shrink-wrapped. Teh box measures 13cm(W) x 9.5cm(D) x 3cm(H). The quality of the packaging is very good.

The top cover is a flap that opens to the left. There is a ribbon loop at the top of the box. I was pulling this for a while trying to figure out what its purpose was. I think it is there to hang the box, perhaps in a shop.

When the top flap is lifted and opened to the left, a warning sticker is the first thing that I noticed!

Underneath the warning sticker is small user guide (which I have not opened to read yet - I wanted to see how quickly I could get the THX Onyx up and running with my iPhone without any instructions).

Below the User Manual is a small flyer about MQA and TIDAL - I already have a TIDAL HiFi subscription.

Lifting the TIDAL flyer out of the way reveals the THX Onyx itself, surrounded and protected by foam.

There are only two pieces of hardware present: the THX Onyx itself and a USB-C to USB-A adapter. The adapter is required if you want to use the THX Onyx with an iPhone - more on that later.

Note that the USB ends of the THX Onyx and the USB adapter have rubber covers fitted for protection. The other end of the THX Onyx has a 3.5mm stereo audio jack for headphones.

Now let's look at the hardware items involved in getting the THX Onyx working with an iPhone.


You will need what known as an Apple Camera Connection Kit (CCK) dongle. There are two versions of this. The USB 2.0 version that is a slim Lightning to female USB-A, and the wider and larger USB 3.0 CCK dongle (this one extends the Lightning port too).

Here's the correct CCK dongle to use (the USB 2.0 'slim'' version):

And this is the WRONG one:

The THX Only apparently only works with the 'slim' CCK dongle.

You'll also need your iPhone, the THX Onyx and the USB-C to USB-A adapter supplied with the THX Onyx.

Here's how the various pieces connect up for iPhone connectivity.

The cabling and adapters add around 13cm (5 inches) to the THX Onyx's overall length. The THX Onyx itself measures approximately 21cm (just over 8 inches). So the total overall length becomes 34cm (almost 13.5inches) which is a LOT!

Let's take a look at how this looks when connected to an iPhone.

Once connected, as soon as the THX Onyx receives USB power from the iPhone, it boots up within a couple of seconds (there's a colourful light sequence from the three LEDs that show it booting up). Once the boot sequence is complete, and no music is playing, a single LED is lit in blue showing that it is ready and powered up.

The headphones that I'm using for this review are the wired Beyerdynamic Xelento IEMs. These are fairly high quality IEMs so often show up bad recordings and playback quality through different audio apps.

Here's the link to the Beyerdynamic Xelento IEMs on the manufacturer's site.


Software - Neutron Music Player and TIDAL

I have both the Neutron Music Player and TIDAL apps installed on my iPhone. Let's start with Neutron Music Player.

Neutron Music Player

Neutron Music Player is an app that I highly recommend for iPhones if you have your own lossless music library. It costs a few British pounds and is well worth the price. I've gone into more details about using Neutron Music with an iPhone in another one of my blog posts on this site:



The stock TIDAL app is also installed on my iPhone and I use it almost exclusively for offline playlist playback with my iPhone.

I had no issues using the THX Onyx with either of these apps. It was plug and play straight out of the box.

Sound Quality Impressions

Before plugging the THX Onyx into my iPhone, I did make sure that my phone's volume was set fairly low (at around 30%). After plugging in, I then made sure that the volume was still low. I did this before plugging my headphones into the THX Onyx.

Through Neutron Music Player, the sound is a significant jump in quality compared to using just the Apple Lightning headphone adapter on its own. Music sounds 'darker', a little clearer and has a wider dynamic range. There's better separation of instruments. The highs are really sweet and full of sparkle. I'd say there is a definite brightness to the music - I only listened to a few CD-quality FLAC files for this review. The sound quality is growing on me with each track that I listen to.

The bass, whilst not that pronounced, is fairly tight. The detail is something that I noticed repeatedly whilst listening to various songs. I mainly listen to Smooth Jazz and something that struck me was that it didn't feel like I was wearing IEMs. The spaciousness of the audio sounded quite akin to listening to speakers. I don't know if this effect is anything to do with the THX AAA amplifier in the THX Onyx.

Vocals are gripping and incredibly lifelike - as if the artist is sitting in front of you and singing for you.

I don't use any EQ so the sound is a little bass-light for me. The mids and highs are more pronounced. I may have to learn how to set up the EQ in Neutron Music Player to lift the lower end slightly.

The LED indicators showed the correct lights for CD-quality music (three greens).

Switching over the TIDAL app, of course, the main point of interest would be the MQA decoding ability of the THX Onyx.

Let's talk about a negative first. During a sample rate change there's a very slight buzz/crackle. For example, when transitioning from a CD-quality song to a Masters track in TIDAL, or vice versa. It's a very quiet crackle and only lasts a fraction of a second, but I can hear it.

My TIDAL playlists contain HiFi quality and Masters tracks, so some sample rate changes do occur in each playlist, but only a handful from playlists containing many hundreds of songs. Playing through TIDAL, the music was still better than listening through just the Apple Lightning 3.5mm headphone adapter. It was step up, but not as large a step as when listening to my local music library via the Neutron Music Player iOS app.

The LEDs light up in a magenta colour for Masters (MQA) songs played in TIDAL.

The treble is very clear. Vocals are quite amazing. Once again, I get that feeling that I'm listening to speakers rather than IEMs pushed into my ears! The sound is non-fatiguing.

A couple of hours into writing this review and constantly listening to my music through the THX Onyx, I'm getting to the point that I don't want to stop listening! It's really growing on me. It has taken me these couple of hours to really appreciate how much the sound quality of an Apple iPhone can be improved upon. It's no match for my dedicated headphones system which comprises of many higher quality components, but for a highly portable system it is very impressive. I do have a dedicated DAP - a Cayin N6ii - that has an ES9038PRO DAC chipset via the Cayin E01 motherboard together with Class A amplification, so I'll need to see how close the THX Onyx can get to the sound quality of a dedicated high-ish end DAP.


With so many bits and pieces connected end-to-end to get the THX Onyx connected to an iPhone, I have to say that the result is quite unwieldy. I'll need to figure out how to tidy up the cabling. Fortunately, all the individual items are small and thin so don't add too much bulk or weight.

It's so much easier and better in the Android world - simply plug the THX Onyx into your Android phone's USB-C port and you're done.

Something to be aware of is that the THX Onyx does get warm. After a few hours of non-stop playback, my THX Onyx has become noticeably warm. It's not uncomfortably warm though.


£199.99 is a lot of money for an external phone DAC. Apple iPhones seem to be designed to be anti-audiophile for unknown reasons! It's incredibly hard to get good sound quality without a LOT of effort. The THX Onyx does deliver a noticeable improvement in sound quality for my iPhone XS Max. I imagine this is largely due to the THX AAA amplifier. The DAC chipset itself is a fairly cheap device but most DAC chipsets these days are generally very good. As always, it's the implementation that governs the improvement in sound quality that you'll get.

My main aim was to get an appreciable improvement in sound quality from my iPhone. To this end, the THX Onyx has delivered. That far outweighs all of the negatives for me.

Is it worth the price? If price isn't an issue for you, then, yes it is worth the price. If you want to drive hard-to-drive headphones, then, yes again. I'll be testing the THX Onyx out with my Beyerdynamic T5p Gen2 closed over-ears. It should be able to drive them with ease as they are only 32-Ohms impedance. I'm also going to see if it can cope with my 600-Ohm Beyerdynamic T1 Gen2 semi-open over-ears.

If you are price conscious and have easy-to-drive, high-quality headphones, you may want to look at DACs like the Zorloo Ztella that uses the same DAC chipset.

I hope you enjoyed reading this review! Feel free to comment - this does require a quick, easy and free registration. Also, check out some of my other posts in this in this blog.