There is something you can use without RCA outputs but I can't remember what it is called. I had it in my car 4 years ago before I had a head unit. It has two wires that connect to your rear speakers and RCA's coming out the other end to plug into your amp. Its the ghetto way of hooking up an amp if you don't have RCA outputs. Go to a stereo shop and ask them, they should have one for sale.