I have an Harmon Kardon AVR20 II, i need help with knowing how many speakers i can have hooked up? On the back there are 2 connections for rear speakers 4 conn. for front speakers, 1 center and a subwoofer. I would like to run two fronts, two rears, a center and sub. But dosent 5.1 mean you can only have five speakers? Any advise would help?