Of course you can! The factory amp has high-level inputs, which you can tap off, as some amps use them, or you can get a high-low level adapter (several companies make these), which turn the speaker outputs into RCA-level music, which any amp can use as its input. You'll need to use some sound deadening material in the trunk to get rid of rattles, if u haven't already. I didn't say "Dynamat", because I only use no-name roofing type stuff. As long as it adds mass to the metal, it won't rattle!