Hi, I have just purchased the Onkyo Home Theater System (HT-S580) from Circuit City a couple of days ago. It came w/ a sub, but I already have a powered infinity subwoofer from a couple of years back. Is their any way to hook both of these up? Would it be ok to plug them both into the sub output on the back of receiver? There is no RCA output for sub on receiver, just one wire output. One sub is powered and the other is not. Also, does it hurt for the powered sub to be hooked up with the wires since it feeds out 100 watts to the non powered sub? I have also purchased Monster XP Compact Speaker Cable (XPMS100) to hook all of this up with. I know this is a bit much but I'm new to this and thanks to whomever can answer.