Is there a way to byp a stock infinity car stereo and install an aftermarket deck?

I have a 2004 Mitsubishi galant gts with a 6 disc in dash cd changer that i don't want to cut out of my dash because i like the way it looks, I was wondering if there is a way i could just install an aftermarket deck underneath the climate controls, i want to hook up an amp and some subs, but don't like the way subs sound coming from a stock system.