Because your aftermarket CD player already has a built-in amp. You need to find out if you have a factory amp, first, though. If you don't have one, you don't need to bypass it 'cause it's not there!
Are you adding anything to your car's system? Like new speakers, CD player, subwoofaz, or amps? If you're not adding anything, then don't bother with the amp bypass. That's only for cars that are adding an aftermarket head unit.
