powering my system

thanks in advance

I have 4 pioneer 12's with a kicker zx1000.1 amplifier. the bass was drowning out my door speakers so i put a alpine mrp-m300 on my interior components. now my subs dont hear nearly as hard as they did before the 4 channel amp was installed. i didnt think that a small amp like that would pull away from the output of the subs. any suggestions to solve my problem would be greatly appreciated.

sn: i have already done a big 3 upgrade and have a optima yellow top battery.

i didnt have to remove the box. i built an amp rack at the top of my trunk where my spare tire is located.