Hands-On Review:Lexicon U42S I•ONIX Interface

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A "fitting" approach to audio interfacing

By Craig Anderton

There’s no shortage of audio interfaces for computers, but Lexicon has come up with a clever variation on a theme with the I•ONIX line. There are three basic models: the U22 with two mic/line inputs, U42S with four mic/line inputs (the subject of this review), and U82S with eight mic/line inputs. The U22, U42S, and U82S all have two Hi-Z instrument inputs and connect to your computer via USB 2.0, allowing sample rates up to 96kHz with 24-bit resolution.

Shapes of things

The first thing you’ll notice is the interface’s wedge shape, designed to fit between your keyboard and monitor. That may not seem like a big deal until you actually install it in your studio—and the controls are right in front of you, while cables trail unobtrusively out the back. It’s easier to place than a standard tabletop unit, and more convenient than a rack unit. The wedge seems like an obvious idea, yet as far as I know, Lexicon is the first to do this.


The U42S also has a substantial feel, so it won’t slide around on your desktop. Part of this is attributable to the weight, and part to the two nonskid pads on the bottom. Furthermore, the front panel knobs have no "wiggle," and the jacks on the back are mounted firmly with locking hex nuts or screws. This is the kind of thing that doesn’t show up on a spec sheet (less expensive models simply solder connectors to a circuit board, with the connectors poking out of a hole on the back) and few people check for this "feature," but it makes a huge difference in long-term reliability—especially if you do a lot of plugging and unplugging.

Making connections

The rear panel has four Amphenol combo XLR mic/line connectors, left and right 1/4" balanced outs, coaxial (RCA) S/PDIF I/O, 5-pin DIN MIDI I/O (thank you—a lot of us use MIDI, despite many interfaces being audio-only). Other rear connectors include a USB port, two +48V phantom power switches, and a power connector for the included "line lump" adapter (unlike a "wall wart," the transformer is located between the AC line and line to the I•ONIX, so it doesn’t take up extra space on a barrier strip).

There are two 1/4" high-impedance instrument inputs mounted on the right side, and two 1/4" headphone jacks (with independent front-panel level controls) on the left, which is another "attention to detail" thing: Almost all headphone cables come out of the left earpiece, and as most guitar players are right-handed, the guitar’s output jack is on the right—so they both plug into the "correct" side of the interface. Little things like that impress me, as it shows the designers were paying attention to detail. And the jack labels are on an angled back surface, so you can peer over the top of the interface, and easily see which input relates to which cable.


Incidentally, a front-panel monitor mix controls mixes between DAW playback and the direct input signals, thus allowing zero-latency input monitoring.

Lexicon IONIX U42S Desktop IO 4X2 with USB 2.0

Lexicon I•ONIX U42S USB 2.0 Audio/MIDI Interface

The sound

None of this would mean anything without good sound quality, and again, I•ONIX comes through thanks to high-voltage dbx mic preamps. If you’re looking for mic preamps with "character," these aren’t the droids you’re looking for—the preamps are clean, clear, and difficult to overload (although they don’t have the gobs of gain some other preamps exhibit). Of course, if you have some favorite funky tube preamp you’d prefer over the "straight wire with gain" approach, you can patch it into an I•ONIX line input.

The compromises

Given the sound and build quality, it’s reasonable to ask where compromises were made to meet an affordable price point. The main ones are:

  • Plugging into instrument input 1 and/or 2 disables mic/line inputs 1 and/or 2. This is to be expected, given that Lexicon promotes the U42S as a four-input interface. There are two small LEDs underneath the two level controls for inputs 1 and 2 that light if the instrument inputs are being used.

  • +48V phantom power is enabled in pairs for inputs 1/2 or 3/4, not for individual inputs, and can only be enabled or disabled from the rear panel.

The software

Drivers are available for Windows XP, Vista-32, and Mac OS X 10.4.9. The Mac specs say an Intel multicore processor is required, but I also tried the drivers on a dual G5 and they worked. Curious, I called tech support (who answered in less than 90 seconds). The tech said that while some people report the drivers working with PPC machines, results aren’t guaranteed. However, the next driver build (which may already be available by the time you read this) will accommodate PPC Macs, as well as 64-bit Vista.


Bundled software includes Cubase LE4, Lexicon Pantheon II AU/VST reverb plug-in, and Toontrack’s EZDrummer Lite (with Cocktail EZX expansion pack).


There are other cool features: The U42S can serve as a four-channel mixer independently of the computer (e.g., keyboard rigs, or a solo act using, for example, drum machine with stereo outs, mic, and guitar). There are also eight-LED input meters and stereo output meters, as well as stereo mode buttons for the two input pairs.


When I first saw the I•ONIX at Winter NAMM, I was intrigued; so when Musician’s Friend asked if I wanted to check one out, I said sure. But I’ve been surprised by the ergonomics, sound, and build quality, all of which exceeded expectations. The I•ONIX may not have the bells and whistles of some other interfaces, but it delivers the goods where it counts.