i have a 12" kicker l7 powered by a kx1200 in a sealed box and the gain on the amp is set on about half. well i have a mustang with the mach 460 stereo so i just have a line out converter to make the amp work. well i had my system on today and i was adjusting the gain and my sub started cutting out and then it would start again. i opened my trunk and looked at my sub and it kept moving in and out. was this clipping? if so, what can i do to prevent it?