I currently have a Polk Audio RM6500 speaker system, utilizing 4 sattelites(2 in front, 2 rear surrounds), a polk center, and a Yamaha sw125 sub. Recently purchased an HK avr525 receiver. I want to add two more speakers for a 7.1 setup, which I am assuming need to be placed at the sides of the room. I am looking at Axiom QS40. Am I better off putting the Axioms in the back(behind main listening/viewing couch)and moving the Polk sattelites to the side, or just putting the Axioms up on the side walls, or does it matter? Help!