Universal Audio Apollo x8 Gen 2 — A Mix Real-World Review

New York, NY (March 21, 2025)—Universal Audio recently released Gen 2 of its Apollo X interface range, adding features and improving the specs of an already stellar line. Like Gen 1, the Gen 2 lineup features Thunderbolt 3 connectivity and supports up to 24-bit, 192 kHz resolution. The line, which supports both Mac and Windows, includes desktop models Twin x Duo, Twin x Quad and x4, and five rack models: the x6, x8, x8P, x16 and x16D (the D is for its Dante connectivity).

UA changed the finish from Gen 1 to a lighter shade of silver—a nod to the original Apollos from 12 years ago—and updated the buttons and knobs. Otherwise, the physical layout of the devices, including the I/O and metering, has remained the same.

The company loaned me a x8 Gen 2, one of the rackmount Apollos, for this review. While it will be the focus here, most of the new features are available across the Gen 2 range, and one, Apollo Monitor Correction, is even backward-compatible with the Gen 1 units.

The interface connects to your computer using a Thunderbolt 3 cable. Such cables are relatively pricey, and considering the cost of these interfaces, UA really should include one.

Like its Gen 2 siblings, the x8 supports 24-bit, 192 kHz resolution. Like the other rackmount models in the line, it offers six cores of DSP. The total I/O count on the x8 is 18-in and 24-out if you include the ADAT and S/PDIF digital ports, which, when connected to a compatible outboard device, adds 10 additional inputs and outputs.

The unit can handle up to eight channels in and out of analog audio. On the input side, you can use any combination of its four XLR mic inputs, eight 1/4-inch TRS line inputs on the back panel and two front-panel 1/4-inch Hi-Z instrument inputs. The outputs, all DC-coupled, include 10 1/4-inch line outs (including the two monitor outputs) on the back and two individually addressable stereo headphone outputs with volume controls on the front.

To get the most out of the interface, UA includes a powerful companion app called UAD Console, which you use for monitor control, creating monitor mixes and accessing various other consequential features. Each input channel in Console contains four insert slots for recording or monitoring through UA plug-ins, plus one slot for a Unison preamp plug-in. The latter allows you to record through UA’s Unison preamp plug-ins, with control of gain staging and impedance from Console or the interface itself.

Thanks to the conversion improvements, the Gen 2 x6 and x8 models have enhanced dynamic range and lower THD across multiple inputs and outputs. UA improved the conversion on the Twin x and x4 desktop interfaces even more dramatically, bringing them into rough parity with the rack units. As a result, any new Apollo you buy will be in the upper echelon of professional audio interfaces in terms of audio specs.

SONAR READINGS

The most buzz-worthy addition to Apollo x Gen 2 is Sonarworks integration. Dubbed “Apollo Monitor Correction,” it stems from a collaboration between UA and Sonarworks. For those unfamiliar, Sonarworks SoundID Reference software provides acoustical correction of your monitoring space and headphone optimization for many popular headphone models.

For the former, it sends test tones through your monitors and instructs you to place a measurement microphone in multiple locations. The measurements it takes are used to create a correction profile, which compensates for room anomalies such as room modes and flattens out the frequency response overall.

When used on its own, you’d typically place SoundID Reference on a DAW’s master bus or as a “Systemwide” app that impacts all audio on the computer. When it’s on the master bus, you must remember to bypass the plug-in when you bounce, or the compensation it applies—which is strictly for monitoring—will get printed.

Apollo Monitor Correction, which will also work with Gen 1 interfaces, allows you to embed your Sonarworks correction profile in the interface. For headphones, the correction is placed at the headphone output, and for speakers, it is placed at the monitor output. Therefore, its processing does not impact your bounces, creating more of a “set and forget” workflow than is typical with SoundID Reference.

You can simultaneously embed presets for both monitors and headphones, so you don’t have to switch between them like you do when running SoundID Reference natively. You can turn it on and off and switch between profiles inside the Console application.

On the rackmount interfaces (both Gen 1 and Gen 2), you can even have a different preset for each headphone output. I’ve used the SoundID Reference plug-in for several years, and its implementation in Apollo Monitor Correction is significantly more convenient.

However, an additional purchase is required. You must buy SoundID Reference and add another $79 to get the Apollo Monitor Correction license from Sonarworks. If you’re an existing SoundID Reference owner, you only need to spring for the license.

GAINING THE SYSTEM

Another useful new Gen 2 feature is called Assistive Auto Gain. Controlled through the Console app, it creates a custom input gain setting based on the input source level. To use it, press the Auto-Gain button on the Console channel you’re recording into. The Auto-Gain floating window opens. By default, it listens for 10 seconds before creating its setting, but the duration is adjustable.

When you’re ready, press the Start button and begin playing, singing or speaking. Within the specified time frame, Console sets the input level on the Apollo. I almost always found these automatic settings usable, with plenty of gain and no clipping. Naturally, that assumes your instrument or vocal level stays in the same neighborhood as what you input during the level check.

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When I first learned about this feature, I thought, “I can set my own levels; why do I need that?” However, once I tried it out a few times, I realized that quickly nailing accurate input-gain levels sped up my workflow. I didn’t have to go back and adjust the input nearly as much as I would have had I been setting levels manually.

Assistive Auto-Gain works with some, but not all, of the Unison plug-ins. Currently, it’s only compatible with Neve, SSL and API plug-ins.

MANAGING DOWN, GRAVY ON TOP

Another new feature is Bass Management, which is designed to make integrating a subwoofer into your stereo or multichannel monitoring system easier. It can be controlled through the Monitor Controller window in Console. It’s also backward-compatible with Gen 1 interfaces.

With Bass Management enabled, you can select one of three crossover frequencies: 80 Hz, 100 Hz or 120 Hz. The steepness of the crossover filter slope is adjustable between 12 and 24 dB/octave. Whether you add a subwoofer to a stereo monitor pair or to the LFE channel in a surround setup, Console will send the low-frequency signal to a designated line output on the back of the Apollo.

When you purchase an Apollo Gen 2 interface, you get the UAD Essentials + Edition bundle, which includes 32 plug-ins in various categories.

Like the Gen 1 Apollos, the new models offer tight integration with UAD’s free LUNA DAW. This includes support for Unison preamps, automatic input configuration, control of DAW parameters from Apollo hardware and more.

THE EXPERIENCE

For the past two months, I’ve used the Apollo x8 Gen 2 as my primary interface. I’m quite impressed with its design and workflow. Recording and mixing with this interface is like driving a luxury car. The sound quality is excellent, and virtually every feature you might need for recording and mixing is available and intelligently implemented.

That implementation includes the way the hardware combines with the Console application. Tracking through UAD plug-ins—both Unison and otherwise—in the Apollo environment is seamless. It doesn’t require that you create aux tracks and buses in your DAW, as you must do to track through plug-ins on most interfaces. Using Console’s insert slots, I could easily record electric guitar and bass parts through UAD amp sims, which is a handy option.

Apollo Monitor Correction is a convenient way to integrate Sonarworks SoundID Reference correction into your system. I’m happy that UA also made it compatible with Gen 1 interfaces. Not all manufacturers would have done that, and it shows that UA respects the significant investment its Gen 1 customers have already made.

The other new features, like Assistive Auto Gain and Bass Management, further enhance Apollo’s capabilities.

I highly recommend the x8 or any of the Gen 2 units. They’re not inexpensive, but between the pristine audio quality, comprehensive feature set, and the whole UAD ecosystem, you can be sure that your money will be well spent.