Audio Systems: subs and amp problem, watts rms, alpine head unit

Question
wats up Scott, i have a problem i have 2 kicker L7s, 2 1400 autotek mean machines, an alpine head unit, i have a capacitor, and an optima yellow top battery. every time i raise the volume past 20 it shuts off, the light on the amp will go red. i know im not maxing it out,  i don't know what to do. wat do you think? do you think it can be the alternator? can you please help me. thanks

Answer
I need to know how you have the subs wired and if you have the 4 ohm or 2 ohm version.

I also need to know the efficiency of the amps, the total watts RMS and the current amperes of your alternator to figure if it's a power issue.

List model numbers when possible. The more I get, the better the answer.