The Mojo opto switching board is a highly configurable switching system for your amp. It allows a variety of switching options while remaining as transparent as any resistor in your amplifier. Opto switching has a soft switching effect, like a pan control turning one channel down and one up at the same time. If you are looking for faster switching the Mojo mosfet switcher
may be a better choice for you. But if you like it smooth go with the opto. The Optoswitcher is also great for series resistance switching.
Documentation: Opto Switching Document
, Mojo Optoswitcher
Kit includes:  6v led optoswitcher modules,  6v led panel mount red, and complete documentation (listed here)