I tried to wire it to the factory JBL amp using the Metra harness, but it had a nasty popping noise when turning on/off and when changing tracks/sources. After lots of research, I soldered in-line a 1.5k ohm resistor in and a 12/5V regulator into the amp turn-on lead, but none of that made any difference. I gave up and just re-wired all the speakers directly to the head-unit.Soldering and testing the wiring harnesses, installing and rewiring the speakers, and installing the head-unit took 12 hours - not the hardest installation I've ever done, but it's up there.I left the factory amp and wiring in tact, just in case...