Sorry the rest of the reply got cut off,
You will just have to be careful not to turn (select) 2 receivers at once. I think that to do it the way you want via a dedicated switch for multi amps is very expensive. You will find some by searching google for "multi source selector" but I do not think that you want to spend that much on this, or do you?
regards
John.
PS. I will be away for the week, and will catch up with you when I return. Good Luck with this, if you cannot find anything let me know I will see if I can make you something relatively cheap.
