Originally Posted by Eracer76

When you hook up your new radio to the factory wires with a harness adaptor, you use the speaker outputs (amp) of the new radio...
So you'll actually be using both amps, which may sound weird but it works fine, its done all the time in many cars that have amps hidden away.

I'm a mobile electronics installer, so if you have any questions, I'll try to answer them when I can.