If the amp has any sort of thermal protection, we will assume that the fuses aren't blowing from increased current draw through heat.
Check your connections, behind the radio.. at the amp, etc. look for loose positive/powered wires to be touching the amp, or the chassis behind the radio.
The amp would, in theory, shut DOWN before it blew a fuse. Replaceing a fuse isn't FIXING the problem. a fuse isn't a first line of defense/air bag. its just a warning, and safety mechanism to protect the amp until you REMOVE the factors that cause it to blow.
