I just bought a Pioneer VSX-D412, and I'm having a bit of trouble hooking it up. I bought it used, and there is no manual. I have a 12" sub, but it is not powered. I have an RCA cable that is bare wire on one end, which hooks up to my sub, and the other end, the RCA jack, is in the subwoofer preout, but I do not get any sound from the sub. Does my sub have to be powered in order for the sub pre-out to work? Do I have to be in a certain sound mode? Is an RCA cable the wrong cable to use? Any suggestions would be greatly appreciated