My first adivse is to check to make sure there are no power to ground shorts or any shorts for that matter. Then, a possibility would be if you have too small of fuses. Make sure you put the correct fuses in in amp according to the manufacturer's specs and the fuse under the hood should be size of your fuses on your amp added up plus a little extra. Meaning if you have 2 25A fuses on your amp then you probably want around a 60A. What ever you do don't put bigger fuses in the amp than the manufacturer specifies or you will cause damage if something gets shorted. Another possibility is that you could have the speaker impedence too low and the amp isn't stable at the impedence you have it at. I hope I could help. Let me know if you need me to specify more. Good luck
-Andrew Hawkins