Monsoon/Aftermarket stereo

[Spilly]

Okay, I'm not new to car audio at all, but I am new to factory amps. I've done some searching here but can't really get the answers I'm looking for.

First of all, I have the monsoon amp. My 6x9's are blown, now I know I can't just throw in any regular pair of 6x9's to replace them, but seeing how both factory speakers are blown, if there an aftermarket replacement that is wired for the factory amp? I would like to replace my head unit, keep the factory amp for the speakers and then run an aftermarket amp for 2 10"s in trunk eventually. Can I run an aftermarket deck through the factory amp without any major modification? Other than the usual chime/wire harness adapter?