I need help in putting together a single source multi-room audio system for my retail store. I need it to cover 4 interior rooms and possibly one set of speakers for the back outside area. My plan is to have XM/Sirius and a hookup for my ipod as well. I already have an existing Sony 5.1 receiver that should work fine for stereo use, but need a cost effective way to control several sets of speakers and would really like independent volume control. I am thinking 6.5" in-ceiling speakers, and a surface mount set for outside. What is my most cost effective option on connecting all of the speakers to one receiver? Any other input would be greatly appreciated as well.