The best way to connect it to a factory system is to tap into the stereos speaker outputs for the amps input signal. Then send the amps outputs back to the stereos harness, and on to the speakers through the factory wiring.
How do you wire an aftermarket head unit to an amp?
Wiring It InCut the insulation off the end of all the wires and leave enough space to attach connector plugs. Connect the ground wire to a metal point connected to the cars chassis or a dedicated grounding point. Plug your RCA leads, speaker leads and remote turn-on lead from the amp into the back of the head unit.More items •27 Mar 2014
Do you need an amp for aftermarket speakers?
A: In most cases, yes. Aftermarket speakers will certainly sound better with a little more juice, but most of our speakers will sound just fine with factory power. Low-efficiency speakers can sound great, but theyll need a high-powered receiver or amplifier for energy.