Hi i am wanting to wire a 4 channel amp up to my door speakers. I was wondering if i could wire the amp up to my factory door speakers???(i believe there factory but idk) i just want to be able to turn it up louder and it to still be a crisp sound. i was thinking about getting a alpine 4-channel amp. Plus im also going to buy a headunit. i have a used small kicker mono amp. could that work?