Thanks for the response. Not a lot of specifics yet. Having a poolhouse/workshop constructed and will have wal/ceiling mount speakers. In the main room 5.1 speakers and a line out to a amp. powering a speaker selector and 12 speakers. Thought it would be nice to use the rear surrounds to play background music if not being used for the surround system. Was trying to avoid adding extra speakers.
This is where you are confusing me...
If you have a 5.1 system, you would have surround speakers, not rear surrounds. Rear surrounds, or surround back speakers, are generally the speakers which are part of a 7.1 setup. It is just confusing me a bit, but I'm rather easily confused.
If you mean you would like to use your surround speakers for background music, then you can't easily do this without a proper relay system in place which would definitely be break before make (break the old amp connection, make the new amp connection)...
But, why not just use all five speakers in the surround system and turn the volume down and run it as 5 channel stereo? You should get far better low-level audio in the space for parties and general usage.
I have it setup this way on my home system for my 'party' input on my receiver and it works great. No extra buttons to hit or dials to turn, just turn the receiver on, put it on the 'house music' input, and I'm done.