If you are adding an amp and sub to a factory premium sound system with its own stock subwoofer, you must get your signal for the line output converter from that subwoofer. Adding an amp and subwoofer to a stock radio can be the easiest way to improve your stereo system in your car, if you do it correctly.

How do you hook up subs to a factory radio?

The Installation Process of a Powered Subwoofer to a Factory StereoStep 1: Place your sub in your vehicle. Step 2: Disconnect the battery. Step 3: Run your amp wire. Step 4: Run the turn-on wire and signal cables. Step 5: Connect the ground wire. Step 6: Handle the wiring connections. Step 7: Get into the music.