Okay, feeling a little dumb right now, but I cannot work out what cable I need to connect my subwoofer to my av receiver. The sub (cheap cambridge audio) has red and black bare wire connectors and the receiver (sherwood r-956) seems to only offer a single rca input. Both manuals are next to useless, unless I am reading them wrong. I currently have some regular speaker cable running around the room to the sub and would like to use that if possible. Any suggestions?