looking for a little info on after market stereos. im thinking about replacing the factory alpine unit with a newer aftermarket usb/bluetooth unit. The car has the factory apline system with the factory sub. my question is is the sub run off a separate amp or is the amp built into the unit. im sure someone has done it and even worse case senior having to install an amp isnt a big deal. just wondering if any one has done it and has any info before i start the little project.

 

1 amp runs both the speakers and the sub. The amp is located behind the side panel on the drivers side of the rear seat, just under the driver side rear quarter window.