I have a sub out connection on my receiver that I use to hookup my (go figure) subwoofer. It is 1 plug coming out of the receiver and 1 plug going into the sub. My current sub cable is 20 ft long but not long enough. I want to move my sub behind my sofa but cannot find a sub cable long enough. I have heard that I can use coaxial as a sub cable and plan on running that through the attic to get my sub where I want it. I know there are several different types and ratings of coaxial cable so I would like to know what type I should be using to connect my sub. Also, do I just use 1 RCA connector on each end? Is there a coaxial to rca adapter?