I second that, if it works perfectly at low volumes, it is most likely the gain. Same thing happened to me, I turned my gain down, and I have never had the problem since. I set my gain by ear when I first installed my system. It worked without a problem for almost 4 years. the problem with my subs cutting out started about 3 months ago, and once I turned the gain down it was fixed. If you have somewhere you can go where you can crank it as loud as you like to listen to it, but have your car parked and watch your amp, you can look to see if it is going into protect mode. If so, it's your gain. Also, touch the amp and see how hot it is, if it's really hot, it's probably going into protect.