I plan on installing an in-dash screen in my truck near my Pioneer Premier CD player (DEH-P740MP). It has 3 RCA pre-outs. My CD player already has 2 amps hooked up to 2 of the RCA pre-outs. If I want to hook up a DVD player or Xbox to the screen, how will I get the sound to play through my speakers? Does the screen hook up to the 3rd RCA pre-out on my CD player? Thanks.