PreSonus Quantum

Thunderbolt audio interface

PreSonus Quantum

Review by Russell Cottier

The new 26x32 channel Quantum is PreSonus’ fastest interface yet. Whilst it works with any DAW the design and integration aims to make usage ideal for Studio One users. With several connection types to choose from PreSonus has chosen the super-fast Thunderbolt interface for this unit and as a result users can stack units to offer up to 96 channels of I/O and high resolution audio through a single cable.

The PreSonus Quantum is an affordable interface but hosts an array of connectivity. The 1U black brushed-metal front panel houses inputs, a display window, several control knobs and two headphone outputs. It is flanked by two silver rack ears that can be removed and the unit comes with rubber feet for a more “desktop look”. There are two mic/line combi XLR/TRS inputs on the front panel which can be used in high impedance mode by pressing the adjacent illuminating Instrument button.

A central display window offers seven-segment LED displays for preamp number and gain level, which is set with the adjacent rotary encoder and selector buttons. The encoder feels fairly robust though the rubber buttons controlling preamp selection, 48V and control room options are less rigid. However, from experience reviewing other PreSonus products with similar controls they seem to hold up quite well. The gains can be set between 0 and 60, it would however have been nice to scale the encoder so there was a little finer control, perhaps a later firmware update will do this. A pad function does not seem to be available either but was not called for during testing.

The control room section that also sits on this central window is really quite useful. The Dim/Mute button can be tapped for Dim or held for a second to Mute the Main Output and the Mono control is great if you are mixing on a DAW that does not offer a simple mono check button. It is refreshing to have such simple front panel controls and the Talkback Mic (recessed into the front panel) is a welcome addition. This inclusion of control room functionality seems to be popular in modern interfaces at the moment allowing project studios to streamline their hardware into a single unit.

Adjacent are a set of dot style input meters, which also indicate whether phantom power is applied to each preamplifier by a blue light above the meter. Whilst there are only 8 points on each meter they are actually quite intuitive to use. The meter dots seem to be faced in the same transparent rubber as the buttons, so care should be taken to not rub these too much to ensure long life.

A large flat grey knob gives main output control level ranging between 0dB and -80dB, it is fairly light plastic but the recessing into the front panel should keep it in place even with rugged use. Finally we have two headphones output with smaller knobs to control level, again these are analogue pots rather than encoders. The headphones can be assigned to any output and there are dedicated headphone outputs that appear in the driver, a very useful feature for monitor mixes. The headphone amplifiers are nice and loud and could easily be used for drum tracking or splitting a single output to a couple of sets of headphones if needed. It should be noted though that the control software for the Quantum offers neither CPU nor DSP mixing so monitor mixes need to be set in your DAW, this includes talkback routing.

PreSonus Quantum

The rear of the device is very much as one would expect — usefully, MIDI DIN sockets have been included. The unit is powered with an in-line adapter and offers dual, stackable Thunderbolt connections allowing you to run up to four units in a row for 96 channels of I/O. There are four ADAT ports giving a total of 16 channels each way at 48 kHz, or eight channels at 96 kHz. The interface is capable of 192kHz operation via the analogue I/O. There is even Word Clock and S/PDIF I/O which seems lacking from some more affordable units on the market, so this could be used to add additional inputs to your Word Clock synced setup, maybe in a larger studio.

The eight outputs are presented as TRS balanced sockets with a separate Main Output pair for your monitors. It may have been useful to have an alt monitor output also, with a switch on the control room section of the front panel for this. Finally the mic/line inputs are presented on combi XLR/TRS sockets.

Before use the device should be registered on your PreSonus account and you will be able to download the Universal Control software. This package allows firmware updates and direct control of routing and gains from the computer. At the time of review the Quantum ships with the Studio Magic Bundle and a licence for PreSonus Studio One Artist (the basic version of PreSonus’ DAW). The plug-in bundle gives users seven plugins in all the major formats from SPL, Lexicon, Eventide, Brainworx, Arturia and Mäag Audio. The bundled software is beyond the scope of this review but is a nice bonus for those setting up a new project studio.

In use the Quantum actually behaved quite well, the preamps sound great for a unit of this price, although the ADCs don’t seem to cope with being overdriven, this could of course be a seen as a bonus as it is hard to not notice anything more than mild clipping. Noise floors on the inputs and outputs seem reasonable and it was not difficult to make good quality recordings with this interface. There are a few nice features as regards the inputs, whereby the unit detects the type of connector inserted and will offer either gain control or selection between -10dBv and +4dBu. When Instrument is selected on the front panel the jack input selection gain becomes continuously variable as you would expect.

For DI guitar recording the instrument inputs held up well, though perhaps not quite as sweet sounding as some dedicated DI inputs and higher-end interfaces. The impedance is high enough to give passive instruments a robust sound and the noise floor is low enough to offer clarity even with very high gain amplifiers.

Operation in the heat of a recording session was simple due to the basic nature of the interface and deeper control like headphone output feeds can be selected from the Universal Control Software. Akin to the hardware this software keeps all functionality close to hand and PreSonus have a general two clicks policy to change any parameter. There is also a rather useful RTA panel which offers not only spectral analysis but also loudness monitoring in RMS or LUFS. There is a K-Meter for those who use calibrated monitoring environments, plus a useful a phase correlation meter. By selecting “always on top”’ in the settings this RTA can become a useful addition to your workflow and can be assigned to any input or output.

Overall the Quantum is an effective interface and a pleasure to use, though the design aesthetic is perhaps not for everyone. The preamplifiers hold up well against some more expensive interfaces and the outputs offer plenty of headroom. Priced at £1050 it is very competitive compared to higher-end units with which it perhaps is hoping to compete, but there are definitely similarly specified interfaces from other main brands that come in at a lower cost. Heavy integration with the Studio One DAW is a definite attraction for existing users and, despite the lack of internal DSP, the unit offers everything needed for an effective B studio, project studio or writing room. Stack a few of these together and you have enough I/O for live band recording.