Help with my car audio and wiring?

So I am putting subs and what not into my car and instead of getting an aftermarket stereo, I decided that I want to get a sounndprocessor so that way I can keep all my steering wheel radio functions and the disc changer. I already found a sound processor that will be good for the price but I am unsure about the wiring. Do I need to buy seperate wiring for the sound processor? And if so, can anyone send me a link to some nice wiring for a good price for it?