The Carl Martin Rock Bug is an amp speaker simulator and headphone rehearsal unit that operates on a single 9v battery. Just plug your guitar (with or without pedals) into the headphone amp's unbalanced 1/4" input, plug your favorite headphones into the unbalanced 1/4" output and off you go. Adjust your guitar's volume with the headphone amp's Guitar knob, select an open cabinet or closed cabinet simulation with the mini-toggle switch, and wail away through the privacy of your headphones. If you like, use the Carl Martin Rock Bug's AUX stereo inputs with an MP3, CD or DAT player, and either play along or add a personal touch to your prerecorded backing tracks. Thanks to the balanced XLR output, you can connect your Carl Martin Rock Bug headphone amp to a mixing console for recording, solo gigs accompanying prerecorded music, or as a DI for live performance if you're packing light or your amp goes down.