it depends on the RMS of each speakers you want to amplify. If you plan on amplifing your speakers you should replace the stock speakers. Like the two rear ones with bigger 6x9s and the front ones (usally 5 1/2" or somewhere similar). Get a capacitar that can distrubute to two amps both two channel amps that match RMS with both speakers RMS you plan on hooking each up to. Of course to do this you will need a quality headunit that will offer good pre-amps for rear, front, and sub amps.