I had my home built in 2002 and had it pre-wired for rear speakers and a run for a subwoofer in the rear wall of my family room. From what I see, it appears most subs/receivers that I've come across use an RCA cable as the connector of choice. Unfortunately, I don't have an RCA input in the wall. Instead, I have 2 cables, each of them consisting of 4 wires (black/white/red/green). How can I possibly set this up so I can use my pre-wire? Thanks for any information you can provide me.