Re: Does any 7.1 AV receiver have selectable rears in 5.1 mode?
Not sure this is something you can do w/o physically plugging/unplugging speaker connections on most receivers/pre-pros.
The only other way I can see you being able to do this is if you have additional, programmable zones on your receiver/pre-pro. My Halcro has an additional zone for a pair of speakers that you can program with any sound info. you want. For example, I am able to mix sound to get an output of 50/50 front and surround for side-fills.