Since I am replacing my rockford 2 ch amp and adding tweeters along with a 6 1/2" sub Would it be wise to just buy a alpine 2/3/4 channel amp and utilize the other channelsfor the tweeters and small sub?
I can get a 4 channel for a few bucks more than a 2 channel anyways

 

Yeah, sounds good. If the sub is dvc, use both channels (3 & 4). If not, bridge it. Sounds like a solid plan and also allows for future upgrades if you decide to push four regular speakers.