Why is my Bass Cutting out?

I just installed a 1800w Kenwood KAC-9103D amplifier and i have (2) KFC-W3012 Kenwood 12 inch Subs running off it. I also have a 800w Kenwood KAC-8403D Im using all 4 guage wire for power. and i have a one 4 guage ground running to my chassis and split into two 8 guages to the amps. I have my settings on my 1800 watt decently cranked. as well as the 800 watt. and let me tell you. It Kicks! ALTHOUGH. when my volume is cranked high on my radio and certain songs hit low notes. the bass cuts out. i turn the volume down and withen 30 seconds the bass comes back on. Im driving so idk if the protection light comes on. ill have to look into that and i have absolutely no dim on my car. my lights. headlights. everything runs fine. should i turn settings down a bit? maybe do the big 3 upgrade?