so i hooked up an amp and sub to my stock unit today and after doing that it worked flawless. Only one problem though. I had a continuous beep beep beep from the left front speaker. I played with the amp a little and it still wasn't eliminated. It only comes on when i am playing a CD. On radio the beeping is gone. I am using a 4 channel LOC and tapped in the stock wiring harness properly.