I have a Carver amp/receiver withy phono, cd and tape inputs, two sets of speakers A and B. From time to time the right speakers (or the left) will simply go out. What is wrong?
It sounds like you may have a corrosion problem with one of the knobs or switches on the amp. You may also hear a "scratchy" sound when you turn the volume or balance knobs.
I have an old Kenwood amp that I use for my studio monitors that has the same problem. When I flip the switches and turn the knobs back and forth it usually fixes the problem and everything works fine... ...for a while.
Try using DeoxIT on the knobs and switches on the amp. It will clean up the corrosion and should fix the problem with the speakers cutting out.