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Swissonic USB Studio D Audio Interface

It is no secret the personal computer is rapidly becoming the centerpiece of the recording process, especially in home and project studios. The weak link for most users, however, remains the communication with the rest of the studio.

It is no secret the personal computer is rapidly becoming the centerpiece of the recording process, especially in home and project studios. The weak link for most users, however, remains the communication with the rest of the studio. The choice of a sound card – or digital audio interface – can be overwhelming. Options range from the cheap (and horrible-sounding) cards that are standard with most computers to high-end professional workstation products. Few display the exceptional quality and intelligent design of the Swissonic USB Studio D.
Product PointsApplications: Studio, project studio, broadcast production, DJ/remixers

Price: $849

Contact: Swissonic at 800-613-2187 707-577-7691; Web Site


+ Quality workmanship and sound

+ Professional bussing features

+ Reasonable price


– No word clock I/O or MIDI

The Score: A truly well-designed piece of equipment. Perfect for compact computer-based studio applications.

The Studio D ($849) is a single-space, rackmountable compact mixer, converter and interface that packs many features into a small package. As the name suggests, the connection with the computer is handled through a single USB cable. The USB standard can handle four simultaneous streams of audio, two in each direction. The Studio D’s basic signal path scheme is similar to an inline recording console, with a monitor bus and a record bus. Most control points are switchable between the two.

The front panel consists of a series of knobs, divided by a stereo pair of eight-segment LED meters. On either side of the meters are the master level controls. To the far right is a control for the monitor outputs, and one for the headphone jack. Three pairs of RCA jacks are present for analog output, one directly from the record bus. The other two (monitor out and line out), are both fed from the monitor bus, pre and post of the monitor pot, respectively. The monitor output can also be muted.

The Digital Out knob controls the level fed to the digital outputs on the rear and has switches to choose sampling rate (44.1 kHz or 48 kHz) and monitor or record buses, as well as a clipping indicator. Digital audio is sent and received in S/PDIF format at 20 bits, with a switchable choice of coaxial RCA or optical TOSlink connections. These digital outputs are actually discrete from the USB data, which is directed through a separate bus.

The unit’s USB port accepts most sampling rate and bit depth combinations up to 48 kHz/16 bit, and can transmit at 44.1 kHz or 48 kHz at 20 bits. USB audio is controllable via two level adjustments – “Computer” for input, and “Rec Level” for output to the computer. This output is always drawn from the record bus.

Most of the front panel – indeed, much of the Studio D’s functionality – is derived from the multiple inputs and mixer section. Four low gain inputs are provided. The two microphone inputs are on balanced XLR inputs, complete with preamps, switchable phantom power, phase reverse and TRS inserts. A pair of high-impedance unbalanced instrument inputs is provided.

One of the unit’s coolest features is a bona fide phonograph input. That’s right, the real thing, complete with phono (RCA) plugs, grounding jack and the all-important RIAA curve. Deejays who are tired of being ignored must be pleased to note that manufacturers are once again paying attention to their interests. The EQ curve is defeatable, for use with tape players, CD decks, and other consumer audio devices.

The inputs are rounded out by four stereo inputs, each of which occupies one TRS 1/4-inch jack: these are line level and unbalanced, most likely intended for use with keyboards, drum machines, and samplers.

The USB Studio D is clearly not for all applications, however. Some users may require word clock and MIDI I/O and, of course, multiple track capability, which this unit does not provide.

In use

Set up is easy; one of the most painless installations I have ever experienced for a computer peripheral. You don’t need tools, you don’t need software – in fact you don’t even need opposable thumbs. Just plug in the USB cable, turn on the computer and Windows recognizes the device and prompts you through the steps. Studio D uses the standard USB audio driver included with your OS. Mac users have it a little harder – they have to go to the Swissonic Web site and download a couple drivers.

In use, the Studio D is a breeze, and very intuitively designed. As I mentioned earlier, the mixer section, despite the lack of such console features as EQ and aux sends, shares an important design element with professional inline mixers: each channel has a Rec Enable” switch that assigns the input and gain knob to either the record or monitor bus, making device monitoring easy.

Each input can be assigned individually to the computer’s recording software. It is just as easy to remove an input from the recording path while preserving your ability to hear it. This simple concept is woefully missing from nearly all lower end and semi-pro gear – I cannot overstate how much this speeds up the tracking process.

Clearly, the designers at Swissonic are familiar with professional design, noted again by the addition of switchable phantom power and phase reverse on the mic inputs. Internally, the discrete USB and digital I/O sections make it easier to keep frame lock with other digital devices. It is nice to move to a less expensive home studio setting without giving up some of the capabilities taken for granted in the control room.

General quality and workmanship are also high – the knobs move solidly and the switchgear and jacks are well made. Swissonic is already known for its high-end line of A/D and D/A converters, and the versions used in this unit are clean and clear-sounding, as are the preamps and gain stages, which have plenty of headroom. Overall, I found the sound quality excellent – remarkable really, given the features and the price point.

The USB audio standard, while becoming increasingly common, is still somewhat novel for professional audio devices. I was initially concerned with audio quality and latency, and was pleased to find that neither were problems. Latency is not really that big of a deal anyway when dealing only with stereo tracks.


The Swissonic USB Studio D is an exceptional piece of gear that is a pleasure to use. It deftly fills the crucial role of gatekeeper between your digital audio software and the rest of your small studio. Creating a home or project studio on a budget makes me want to pull my hair out as I realize how many pro-studio features I will have to give up. In contrast, the Studio D provides professional features like phase reverse, switchable phantom power, inline monitoring, inserts, monitor mute switch and phono equalization.

The engineers at Swissonic should be commended for creating a reasonably priced, compact piece of equipment without giving up professional quality and design.