Sony Xplod 800W Class AB Bridgeable 2-Channel Amplifier w/ Selectable Low-Pass Filter "cant select channels" Questions

channels or discrete is selected, and only can be stopped if speaker is disconnected from right rear socket. I would appreciate any ideas on the possible cause please. Thanks. To the original poster I

...select the various inputs I hear the sound fromthe analog input and I still get the same volume level regardless ofthe input selected. The only change I get is the momentary muting ofthe sound when ...