I have an audiopipe APSM-1300 and its hooked up to an audiopipe 15... I set the gain with a DMM to 31.6volts for 500 watts RMS @ 2 ohms. And when I set it the volume on the headunit was 37. I noticed that, when the volume goes past 42, the power to the sub will cut out for like a half second at a time and the sub will make a popping sound when the bass gets heavy, and I first thought it was just simply because it was too much power for the sub. BUt my friend just bought an L7 that is 750w RMS, and I hooked it up, and turned it up past 42, and it did the same thing, so now i know it's not my sub. Question is, what would cause the amp to cut out like this, its a 600w RMS amp and i have it running at 500 when the HU volume is 37. so 42 shouldn't be too much power for the amp or the MTX sub. Any suggestions? Might it just be something as simple as a bad ground...? Thanks.