The Radial Engineering Backtrack is a stereo audio switcher that provides two stereo input paths via 1/4" and 3.5mm connections, and handles audio from laptops, interfaces, MP3 players, or combinations of any compatible device.
The Backtrack's dual-input function lets you switch between different musical loops, though you can also use the unit to run a redundant backup loop; this is particularly useful if you want to minimise the risk of your backing track suddenly dropping out—a fear any musician can relate to at one time or another.
Once you've connected two audio sources to the Backtrack, you can switch between them, or mute them both as you please. Front panel controls are provided for this purpose, though you can also use a JR-2 remote foot-switch, available separately.
Level controls on the headphone output let you monitor either input whenever you wish, while a 1/4" monitor output can route sound to powered speakers. For the PA system, you'll find dual transformer-isolated XLR outputs, complete with a ground-lift switch to mitigate any noise, buzz, or hum often associated with ground loops.