Or you could use an amp switcher like the niles audio SAS-1 or SPK-1 I use these to switch between 2 amps and 1 set of speakers. http://www.nilesaudio.com/product_de...ems&catcdID=10

you can usually find them on ebay for a big discount. The SAS-1 is probably the better way to go because the SPK-1 is triggered by a 100ma trigger from an amp. If one of your amps does not have a 12v trigger then the spk-1 wont work