The ABY allows you to route one signal to two outputs or route two inputs to one output by choosing A, B or A&B combined. It is powered by a 9V battery or adapter. The built-in LED's clearly show you which signal is active. The unit is true bypass and passive(will work withough power). Power is required only for LED indication.
Do not use this unit on powered speaker lines. You will damage your amp, speakers or both.