Just a quick question? I now have 5.1 with the two rear speakers in the two rear corners. Im purchasing today the Pioneer AX5i amp which Im told is 7 channels. Am I right, is 7.1 adding two rear extra channels to the pair I now have? and if so can I just add the two new channels between the two speakers I now run in the rear corners. As I have some installation problems I really want to keep the 4 rear speakers all on the back wall. Will it work like that?