I bought an Acoustic Research AR1108 at a pawn shop to switch between two sets of tower speakers. It worked perfectly. It has built in protection circuitry. I ran it off my B&K 200w amp. I did not hear any audio degradation at all.
http://www.ambientweather.com/ptrcaar1108.html
http://www.amazon.com/Acoustic-Research-AR1108-8-Position-Selection/dp/B00005I9QH
Bill
http://www.ambientweather.com/ptrcaar1108.html
http://www.amazon.com/Acoustic-Research-AR1108-8-Position-Selection/dp/B00005I9QH
Bill