schoche makes a product that allows you to take speaker wire output from a factory radio and wire them up to their box that will change it to RCA outputs to the sub. Do a search for it in google. I forgot exactly what it is called. I think it is like the SLC-4 or something like that.i can get one hell of a deal on a good amp and subs, but i want to keep my factory head unit cuz i have navi, 6 disc, sat etc, so i am just wondering if i can hook direct up or if the radio doesnt have rca plugs how can i make this work??