So I was looking to replace my 2006 cobalt ss factory radio with an aftermarket one, but whenever I select one on a website such as crutchfield it says it's not compatible with the factory subwoofer. Is that because you need to buy an amp for it to work? I really don't know much if anything about car audio (or audio in general) and was wondering how that worked. Also if anyone has any good recomendations for head units around or under 200 that support back-up cam I'd be happy to hear them. Thanks for any help.