I want to hook an amp up to a stock stereo in a Geo tracker. I have done everything you can do with stereos but never to a stock stereo. This is for my dad and he just want's a little bass not nothing big so I am gonna get a cheap amp and two subs and hook it up to a stock stereo becuase he mostly listen to the radio. So how do I hook the amp up to a stock stereo.

 

All you need is an amp with speaker level inputs and a built in low-pass crossover. I would think that you would already know that if you have "done everything you can do with stereos" though. This is pretty much common practice when adding a sub only.