my friend is looking for an extremely budget friendly surround sound system. So naturally, I turned to eBay. I found these in wall speakers. I plan on hooking all of those speakers up to this Sony STR-DG820 system. The back panel of this system looks like this. I am not sure how I would connect the subs to this receiver. Could I utilize both subs? Or would I have to sacrifice one? Also, are these speakers decent speakers? thanks for all the help.