Hey all, first time poster here, found this site on google. Here is my situation. I own a YamahaRX-V650 7.1 Reciever. I want to have the best quality sound I can with these speakers. I dont have all the model numbers but this was all picked up as a set. I have Polk Audio Floor Towers, Center speaker, 2 R15 bookshelves and the subwoofer. Basically what I want to know is can I purchase 4 more of the R15 bookshelves and use a set as Surround back, a set as the Surround Speakers, and a set as the presence speakers? If so is this a good idea? If not what do you guys suggest?