Wire aftermarket HU into or bypass factory amp???

[CeaseNY]

Hey I have a 99 chrysler 300m with the infinity stock amp in the trunk..i hooked up an aftermarket HU, gets power but no sound which im pretty sure is because of that amp...Ive searched the forums and i saw alot of different answers but none very detailed....i bought the scoche dash kit w/ the wiring harness...everything plugged in good, theres still one adapter that was plugged into the stock HU, with 1 wire on it...i believe thats for the amp...basically, i just want sound...I just need to know how to A.) hook the aftermarket HU to the amp, or B.) bypass the amp, which im REALLY not trying to run new wires through the car, that would be a bitch...please help...thanks!!