Thanks for the replies!
I'm going to look into some new cables asap. I just sold my old guitar so I'm going to spend some of that money on records/record gear. I'm not sure if I explained my speaker system correctly. I think the sub is a receiver/sub. The sub has outputs for speakers and a connector to a volume control/input for whatever you want to play music on. The output is a bit low so I should probably upgrade my preamp, but then I'm not sure if I can use my sub since it has a built in preamp.