Universal Audio Apollo x4 review

Universal Audio’s Apollo range of interfaces gains a new member.

  • £1500
  • €1794
  • $1799
Universal Audio Apollo x4 review
(Image: © Future)

MusicRadar Verdict

With a seductive feature set, it will provide ample I/O for many and, at a lower price than its bigger brothers, will prove justifiably attractive


  • +

    Wonderful sound and ease of use.

  • +

    Four Unison-enabled preamps.

  • +

    Doubles as a monitor controller for multiple speaker pairs.


  • -

    No way to configure the 6 outputs for surround sound.

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What is it?

Universal Audio’s range of audio interfaces has always provided a twin approach to sound recording and processing. In addition to the high-end preamps and I/O you’d expect of a top-end audio interface, they’ve also provided access to UAD’s extensive effects collection. 

They use native processing to reduce load from your computer’s CPU and provide near-zero latency in the process. 18 months ago, the rackmount range of Apollo interfaces was updated with improved audio specifications and Thunderbolt 3 connectivity. 

At that time, the desktop Apollo Twin interface remained untouched by the upgrades afforded to its brothers, but it now gains many of the new specs offered by the rackmount Apollo units. More intriguingly, a new desktop module enters the Apollo family – the Apollo x4.

Like the other units in the revamped Apollo range, the x4 is a Thunderbolt 3-enabled interface and it’s a little less than twice the size of the Apollo Twin, offering a similar desktop, wedge-shaped design with a prominent rotary dial on its upper surface. The front edge provides twin guitar inputs on its left-hand side, whilst two, independent headphone outs feature on the right. 

The x4 is an excellent addition to the Apollo range

Round the back, you’ll discover four Unison-enabled preamps from which the x4 takes its name. Unison is the proprietary emulation technology Universal Audio have developed to model the input behaviour of a range of classic preamps and channel strips, each of whose input levels and settings can be selected and adjusted from the rotary dial and top-panel buttons.

Output-wise, you’ll find six round the back. If your mind has leapt to the possibility of surround-sound configurations, you’re going to be disappointed, as the ports can’t be arranged this way. Instead, a Monitor stereo output pair is flanked by additional Outputs 1-2 and 3-4, which does mean that both effects loops or three pairs of monitors can be driven directly.

(Image credit: Future)

Performance and verdict

Specs-wise, the Apollo x4 offers 127dB of dynamic range and -117dB THD+N, which is a significant improvement from the previous generation of Apollos. UA’s interfaces have long held an entirely justified reputation for an open, warm recorded sound, befitting the company’s origins. That reputation is further enhanced here: the sound is sumptuous.

Also consider...

(Image credit: Future)

Antelope Audio Zen Tour
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Apogee Element 46
If you’re happy with software-controlled hardware, Apogee’s Element interfaces offer glorious audio quality, and the preamps are among the best-sounding available.

And, of course, it’s aided further by UAD effects provision. The x4 comes with a Quad processing chip onboard and bundles some classic effects, including the Teletronix LA-2A and 1176 compressors, 610-B Tube Preamp and Pultec EQs. Many more effects can be ordered, individually and in customised bundles from UAD’s store directly.

The x4 is an excellent addition to the Apollo range. If the Apollo rackmount modules offer more spec than you need, it should prove head-turning and as a desktop front end to a larger system (up to four Apollo units and six UAD-2 devices in total can be daisy-chained), there’s an awful lot to like here.

MusicRadar verdict: With a seductive feature set, it will provide ample I/O for many and, at a lower price than its bigger brothers, will prove justifiably attractive.

Hands-on demos

Universal Audio


The web says

"Despite its compact size, the X4 is a grown-up audio interface with excellent features and superb audio quality. Having the Unison preamps on all inputs is fantastic, and sets the X4 above some of its larger, rack-mounted stablemates..."

"There is clearly a growing market for premium interfaces that can handle critical recording tasks, and if you have that sort of money to spend, the Apollo x4 is a heavyweight contender."
Sound on Sound


  • KEY FEATURES: Desktop 12 x 18 Thunderbolt 3 audio interface, Mac/Windows compatible, 4 Unison mic preamps, UAD-2 QUAD Core Processing, 2 Unison-enabled Hi-Z instrument inputs, 2 headphone outputs, built-in Talkback mic, up to 8 channels of digital input via Optical ADAT/SPDIF input, ‘Realtime Analog Classics Plus’ UAD bundle
  • Universal Audio