Icon Pro Audio/Harrison 32Ci

Boring preamps have long been a given in audio interfaces, but all that is about to change...

Audio interfaces have had mic preamps built into them for almost as long as there have been audio interfaces. But for many years, it seemed as though manufacturers had signed a secret pact to make their preamps as boring as possible. Interface designers were slow to wake up to the fact that not every user wanted a completely transparent, neutral input stage, and that in fact many people were spending really rather a lot of money to augment their transparent, neutral input stages with third‑party mic preamps that offered a bit of character.

In the last few years, we’ve seen a sprinkling of interfaces with transformer‑balanced preamps that can add a little mojo to proceedings, including Steinberg’s UR‑RT models, Neve’s 88M and the forthcoming Heritage Audio i73 Pro. It’s still a surprisingly sparsely populated market sector, though, so the emergence of a new contender is very pleasing.

That contender is a collaboration between a relatively young company, Icon Pro Audio, and veteran console designers Harrison. In some ways, it’s a fairly conventional USB audio interface, but in place of the usual boring mic preamps, it employs the input stage from Harrison’s 32‑series consoles. So, as well as heritage preamps, it has an unusually extensive filter implementation featuring high‑ and low‑pass filters that can be swept right through the midrange. And, as we’ll see, it also has a few other unusual qualities.

Short Back & Sides

The 32Ci is a desktop device with a gently raked, squarish case measuring nearly nine inches by 10. The controls are housed on the top, the two headphone sockets are at the front, and all the other I/O is located on the slightly deeper rear panel. Build quality and industrial design are impressive, and there’s a real sense of class to the 32Ci that belies its competitive pricing.

One reason why boring preamps are the norm in audio interfaces concerns power requirements. As well as offering good specifications, modern off‑the‑shelf, chip‑based designs are very efficient, which is an especially important consideration in bus‑powered devices. If Icon Pro Audio had taken that route with the 32Ci, I’m sure they’d have been able to make it powered over USB, but the inclusion of the Harrison preamps necessitates an external PSU. The unit also gets noticeably warm in use, though thankfully there are no fans to kick in and ruin your best takes.

The 32Ci measures 291 x 243 x 92mm and weighs 1.83kg.

All of the 32Ci’s controls seem to use conventional pots, and there is nary an endless encoder to be seen. The master volume control is flanked by 12 LEDs which act as a pair of six‑segment meters. The two interesting preamps are fed from combi XLR/jack sockets, and can be switched into a high‑impedance mode to accommodate signals from electric guitars and basses. There’s an additional pair of inputs on quarter‑inch jacks; depending on the setting of a rear‑panel button, these can operate as balanced line‑level inputs accepting levels up to +24dBu, or as unbalanced ‘consumer’ inputs optimised for the ‑10dBV standard. On the output side, there are two pairs of quarter‑inch jacks in addition to the aforementioned headphone outputs. These are configured in a slightly unusual arrangement, which I’ll return to in a moment.

There’s also digital I/O, comprising a single ADAT optical in and out, MIDI in and out, and two USB Type‑C sockets. One of these is used to connect the 32Ci to the host computer, while the other is labelled OTG and is intended for streaming audio from the 32Ci to a phone or tablet. If you use an Apple device, you’ll need the official Camera Connection Kit or similar rather than a generic USB cable.

Buffering The Hits

Basic audio interfaces often handle cue mixing and low‑latency monitoring using only hardware controls. As the I/O count mounts up, though, this gets impractical, and so more complex interfaces have digital mixing and routing facilities, configured using a software control panel. The 32Ci is the only interface I’ve come across that falls into both camps at once.

How so? Well, inasmuch as there is mixing and routing functionality built into the 32Ci, it’s all‑analogue and controlled from hardware. However, you can also install a macOS and Windows program called IO Pro. This looks similar to the mixer utilities supplied with many other interfaces, but instead of adjusting settings on DSP in the interface, it runs entirely natively. It’s perhaps best thought of as a host‑based alternative to your DAW’s own mixer window that runs in parallel with your DAW.

The main Core Audio or ASIO driver presents a total of 14 physical I/O paths to and from your DAW at base sample rates (four analogue plus stereo OTG and eight ADAT), while a second ‘loopback’ driver presents four stereo virtual I/O paths, if selected. The 32Ci itself is blissfully unaware of the virtual I/O, but both sets appear in the IO Pro mixer. On macOS, therefore, the IO Pro mixer has a total of 12 mono and five stereo input channels; things get more complex...