Need speaker help!
The reason I ask is there are a lot of things that come in to play that people don't consider. The Monsoon system drives the front highs from the receiver, the mid bass / midrange gets sent to a punny amp in the back. The rears and stock subs go to this amp as well. If you were to put an aftermarket head unit in using the existing wiring you will more than likely be over driving the inputs of the stock amp, resulting in either frying it or a lot of distortion when your system is turned up. This is just one thing to think about.
You can do what dfarmercse said on the connectors.

