Antelope Audio’s latest desktop audio interface, the Zen Quadro, offers an impressive amount of interface for your money.

I’m not sure how Antelope Audio came to choose the name Zen for their range of desktop audio interfaces, but there’s a sense in which it’s quite apt. For most of us, I think, the ideal audio interface is one that we’re not really conscious of. The less we have to think about it, the better, and a perfect audio interface should offer complete sonic transparency and intuitive ease of use.

Antelope have spent many years pursuing the first of these goals, and their interfaces have consistently claimed class‑leading specifications. Much thought has also gone into how the user interacts with the interface, through features such as hands‑on controls and, on some models, touchscreens. Meanwhile, in a less obviously Zen move, they’ve pioneered the inclusion of FPGA‑ and DSP‑based digital effects that can be applied in the recording path, offering low‑latency EQ, dynamics, preamp emulation and much more.

Q To Quadro

The latest interface to bear the Zen name is the Zen Quadro Synergy Core. Viewed from the top, it’s pretty much identical to the earlier Zen Q Synergy Core USB interface reviewed in the SOS May 2022 edition, with the same large and slightly clunky rotary encoder, small push‑buttons and colour display (which is not touch‑sensitive). But whereas the Zen Q has an angled body, the Zen Quadro’s is flat, and although both offer four analogue inputs, the newer model has four mic preamps compared to the Zen Q’s two. The front‑panel combi inputs can still operate in high‑impedance mode for guitar recording, of course.

On the output front, the Zen Quadro follows the Zen Q in offering two pairs of line‑level quarter‑inch jacks, plus two headphone sockets. It also retains the Zen Q’s complement of digital I/O, meaning that there are coaxial S/PDIF in and out sockets plus a single optical input for ADAT Lightpipe. And like the Zen Q, the Zen Quadro is bus‑powered over USB, with no mains PSU socket and no Thunderbolt option, but there’s a significant development here in the shape of a second Type‑C USB port. This allows other USB audio‑capable devices such as phones or even a second computer to be integrated. The Zen Quadro is a class‑compliant device, which uses the familiar Thesycon driver on Windows and the built‑in Core Audio driver on macOS.

Antelope Launcher

A key focus in Antelope’s drive to improve ease of use over the years has been the Antelope Launcher software utility. This doesn’t catapult kudu or hurl hartebeest, but acts as a central hub for everything related to Antelope hardware and software, handling installation, updates, authorisation and more. Once this is installed, getting started should be straightforward, but in my system it wouldn’t acknowledge the review Zen Quadro until I’d visited the System tab and rebooted the Manager Server.

Antelope Launcher... acts as a central hub for everything related to Antelope hardware and software, handling installation, updates, authorisation and more.

Though it’s a separate program, the Zen Quadro’s software control panel can be opened only from the Launcher. Assuming you want the control panel open while you work, this has to be done each time you boot your computer, though it’s possible to save settings within the hardware and even use it standalone if you wish.

The control panel presents three separate mixer panes, respectively feeding the main monitor outputs, mirrored at the first headphone output; the second headphone output; and the second pair of line outputs. There are also routing panes that allows inputs to be assigned directly to outputs. This is useful, because the primary USB port presents 16 ins and outs to your DAW; with up to 16 physical inputs also available, this means there are twice as many potential sources as there are channels in the mixers.

Each mixer pane offers the same selection of 16 mono or eight stereo channels, which are initially drawn from the four preamps, the first pair of playback channels from the primary USB device, stereo playback from a secondary USB device, and the eight ADAT input channels. Sources such as the S/PDIF input are absent by default, and if you want to feed them into the mixer, you’ll need to sacrifice other sources in their place. As well as S/PDIF and additional USB playback channels, other options include ‘emulated mic’ channels for use with Antelope’s Edge mic modelling system, and a choice of two test oscillators. It’s also possible to set USB record inputs to pick up ‘loopback’ signals from the mixer.

The AFX Team

The first six sources in the mixer have insert points for the onboard AFX: signal processing presented in a plug‑in‑like interface, but running on the internal Synergy Core platform. The Zen Quadro comes pre‑equipped with a healthy selection of 37 AFX modules, which encompass guitar amp and cabinet emulation, modulation effects, vintage‑style EQ and compression, preamp emulation, a tuner, and more. Many additional AFX are available as add‑ons. These channels each have eight AFX ‘slots’, which are individually bypassable, and AFX can be reordered by dragging and dropping. There’s no preset structure for individual AFX, but it’s possible to save entire chains as presets, including the settings of the individual modules. A number of preset chains are supplied.

Conceptually, the Synergy Core system has something in common with Universal Audio’s UAD2 Powered Plug‑ins platform, but there are obvious differences. Although there is a global Auraverb reverb, AFX doesn’t otherwise offer time‑based effects such as delays and reverbs; and whereas UA’s Console makes it possible to use UAD2 processing only in the monitor path on a per‑channel basis, AFX are designed to be printed with the source. (It is, however, possible to route each preamp simultaneously to a second USB record destination if you want to record it dry.) The Zen Quadro doesn’t support Antelope’s AFX2DAW plug‑in, which would allow AFX to be used at mixdown within your DAW’s insert points in the same way UAD plug‑ins can be, but you can route USB playback channels from the DAW through AFX and re‑record them or have them running live at mixdown. The AFX devices themselves are generally of high quality, and the collection that comes free with the Zen Quadro is more generous than the Realtime Analog Classics bundle you get with UA’s desktop Apollo interfaces.

There’s no meter that reports what proportion of the Synergy Core processing has been used up, but as I understand it, this isn’t as simple an equation as it is with a purely DSP‑based platform like the UAD2 system. At any rate, I never managed to reach the limit in normal use, even with multiple AFX instantiated on all six channels. In general, the system is well thought‑out, easy to use and genuinely useful; my only tiny gripe is that if you have the control panel window in Compact mode, it’s not possible to tell at a glance whether a channel has AFX loaded or not.

The mic preamps offer a 75dB gain range, in 1dB steps... and A‑weighted dynamic range is given as 122dB on the analogue inputs and a colossal 130dB on the monitor outputs.

Core Strengths

The Zen Quadro boasts remarkable specifications, especially considering that it’s a bus‑powered USB device. The mic preamps offer a 75dB gain range, in 1dB steps, with THD quoted as ‑116dB — equivalent to 0.00016 percent —  and A‑weighted dynamic range is given as 122dB on the analogue inputs and a colossal 130dB on the monitor outputs! These are the sort of specs you’d expect to see on a mastering‑grade converter costing thousands, not a squat black desktop box retailing at only a few hundred. It seems unlikely that most users will ever need quite that much dynamic range, but it certainly fulfils the remit of allowing you to forget about what the converters and preamps might be doing to your sound.

The control panel and routing possibilities strike a good balance between flexibility and ease of use, and although I can imagine circumstances where it might be restrictive for example to have the main outputs always mirrored on the first headphone output, 99 percent of the time it’ll be exactly what you need. Four analogue inputs with mic preamps is enough to cater for a broad range of recording scenarios, and the ADAT input makes it easy to expand when you want to track drums or similar. Though it’s stereo‑only, the second USB input works very well when you need to connect a phone or other consumer source; just be aware that if you have an older iPhone with the Lightning connector, you’ll need to use a proper OTG adaptor such as the Apple Camera Connection Kit — a generic USB‑to‑Lightning cable won’t work. One area where some rival interfaces score over the Zen Quadro, though, is monitor control: there’s independent volume and mute for the monitor outputs and the two headphone outputs, but no dedicated mono button or one‑click speaker switching.

The Zen Quadro Synergy Core offers a combination of features and sound quality that is unmatched for the money, and I’m sure it will be a big success.

The most impressive thing about the Zen Quadro Synergy Core is the value for money it offers, as a glance at the competition confirms. Arturia’s AudioFuse Studio offers more versatile I/O options and also has impressive specs, but is significantly more expensive, as is Avid’s MBox Studio; and although MOTU’s M6 is more affordable, it lacks the Zen Quadro’s digital I/O — and none of these has built‑in signal processing on the same level. If you need that, Universal Audio’s Apollo x4 has a similar basic configuration, with four mic preamps and two headphone outputs. It offers an additional pair of line outs, ADAT Out as well as In, a nicer action on the encoder, the benefits of Thunderbolt connection, and an effects platform that is arguably more versatile than the Synergy Core — but it’s more than twice the price of the Zen Quadro.

In short, although some other desktop interfaces may have an edge in terms of ease of use, I/O count or versatility, you pay a lot more for that edge. None of them betters the Zen Quadro’s audio specs, and none competes on price. The Zen Quadro Synergy Core offers a combination of features and sound quality that is unmatched for the money, and I’m sure it will be a big success.