There's no doubt that tablets and smartphones have made multi-track audio recording on the run easier than ever. But connecting instruments to iPads and iPhones has never been quite as simple. The iRig Pro Duo from IK Multimedia helps make that final connection and allows musicians to truly record on the run.

Free programs like GarageBand can make what was unthinkable a decade or two ago possible for just about everybody, giving the masses the means to record and mix fully professional and finished audio tracks. But hooking up to a portable device like an iPad or iPhone has never been straightforward.

For starters, pretty much nothing in the tablet or phone range has a direct connection for a proper microphone or musical instrument. So we're forced to the "peripherals" market, which is huge. Perhaps that's why working out what you want – and need – can be daunting.

One of the big players in this area has recently come up with a nifty solution where simplicity and portability reign. It's IK Multimedia's iRig Pro Duo, and it's the bigger brother to the iRig Pro, a portable device with an XLR/TRS combo audio jack, phantom power, direct minoring and a headphone jack.

As the name suggests, the Duo adds another input, allowing two devices (whether they be microphones or instruments) to hook up at the one time. Both are powered by "ultra-low noise studio quality IK preamps" and both have individual gain dials. As well as the additional channel, the Duo is also slightly larger. It's a shade smaller in length and width than my Samsung Galaxy Note 3, and about three times as thick. For what you get it's still a relatively tiny footprint.

And although it's clearly an all plastic construction, it appears very well put together and there's enough heft in it to make it feel substantial and solid. The piano gloss front might pick up some scratches over time but, encouragingly, after month or so of reasonably comprehensive use (including some time on the road where the Duo was transported loose in a music bag) our unit remained blemish-free. It hasn't been dropped though, and we expect a decent hit on the concrete would cause some damage to the casings.

In practice, the Duo works in a similar way to the plethora of other audio interfaces on the market, but with a couple of important differences. In addition to being able to hook up two mics or instruments, MIDI in and out, headphone out and direct monitoring (through two balanced TRS outputs), it can also be powered by two AA batteries and was designed from the ground up for portable devices.

The latter two points, along with the size, are possibly the most relevant and help differentiate the Duo from many other offerings in the crowded musical recording space. The end result is that this thing is super easy to use with an iOS device. Or an Android device, if that's your preferred flavor.

Plug one end of the Lightning Plug or USB adapter into your iOS or Android device and the other into your mic or instrument. Then fire up GarageBand or other favorite multi-track recording software and you're pretty much there. There's a list of compatible software on the IK Multimedia web site.

The Duo also has 48 V phantom power built in (switchable – on and off – and available to both channels), a headphone output with dedicated volume control, two generously-sized gain dials (one for each channel) and LED lights showing signal levels as well as the status of MIDI and phantom power functions.

Along with the LED display, the gain dials make finding a good level very simple. It's by no means the most comprehensive metering system on the market, but is surprisingly functional and easy to set. Basically, if it lights up blue it's too soft, red is too loud and green and orange are the sweet spots. It doesn't take long at all to get used to and keep in the corner of your eye while recording.

Sound-wise, we found the Duo to deliver excellent quality recordings. We've tried plugging in everything from a Fender Stratocaster, a vintage Les Paul, a Martin acoustic, a no-name bass and numerous microphones, including our trusty Shure SM58 and, for a condenser mic test, our old Rode NT3.

The quality of recordings surprised us at every turn. Vocals were crisp and clear, with nice dynamics, detail and excellent signal levels. Likewise with the instruments. They just worked and, for the most part, sounded pure and excellent. They really did have a "studio" quality about them and even the weakest signal we put through the Duo was easily boosted. We were particularly impressed with the quality from the Rode NT3.

Like its smaller brother, the Duo is capable of 24-bit digital-to-analog and analog-to-digital conversion and supports sample rates of up to 48 kHz. Now this may not be as high-res as some other units can offer, but it kind of makes sense to use it at this level. Higher quality recordings are rarely essential for home studio use at this end of the market and, to the ear at least, the recording quality is superb. There's also the issue of space. Given the Duo was designed primarily with tablets/phones in mind, and storage space on these devices is a premium at best, it all adds up.

While we didn't get to test the MIDI in/out, all reports suggest they work as expected. It's important to note, however, that MIDI usage is restricted to 5-pin equipped keyboards with their own power source. You cannot a USB MIDI keyboard. Depending on your planned usage, that will either matter a great deal or not at all.

In practical terms, it's quite liberating to be able to record at such high quality while truly being untethered from the rest of the world. The longer you use it, the more applications you start realizing. As a guitar teacher, I found it great to take to lessons and record what we were doing on the student's own iPad or iPhone (providing the student had a device with a Lightning connection, older styles require ordering the optional 30-pin cable).

Recording backing tracks for students on the fly was also a great time-saving/teaching resource. Not to mention backing tracks for my own practice. We also took it out into the bush to record some atmospheric nature sounds with the condenser mic and it worked a treat. We played with it around a campfire singalong so we could relive our moments of musical brilliance in the cold, harsh (and sober) light of the next day. Without its own battery power (which also prevents the Duo sucking up your iDevice's juice), these kinds of recordings wouldn't be possible.

Battery life from the two AAs was excellent, and provided us with hours of use, partly with the phantom power and partly without. Personally, two AAs are also better, cheaper and easier to come by than the usual 9 V battery requirement for similar devices. USB power and DC power are also options (DC power cable not supplied, but a 9 V, 500-mA supply will do the trick).

While it's brilliant on the road, the final surprise was that the Duo also made for an excellent desktop/laptop audio interface. Hooked up to our MacBook Pro (via USB) and using either GarageBand or Pro Tools, connecting and recording was easy (once the correct input was selected in the MacBook's settings).

Indeed, when we're not on the road, the Duo has remained connected to the laptop for quick and easy access when required. Like with the iOS/Android devices, the Duo performed flawlessly with the MacBook Pro. It also takes up very little space on the desk.

While there are better, more comprehensive audio/MIDI interfaces on the market, the top-quality audio, small footprint, battery operation and iOS/Android interface make the iRig Duo Pro a compelling product for amateurs and pros alike.

The unit also comes beautifully presented in highly-designed Apple-like packaging and is available now for US$199. IK Multimedia is also throwing in a load of software and applications, such as AmpliTube Free, VocalLive Free and much more, which it says is worth at least an additional $450.

It comes supplied with numerous cables, including a Lightning, USB-OTG and USB. Connecting to an older iOS device will require purchasing a seperate 30-pin cable. For MIDI, two TRS to MIDI-DIN cables are supplied.

Product page: iRig Pro Duo

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