A higher end amp won't usually help

I have to disagree with that. Cheap amps tend to be less powerful and less efficient so people run them at a higher gain and they tend to overheat. Used to happen to me with a couple of crappy amps. I now have a couple of MTX amps (excellent power for the money) and have no problems. In fact I store a blanket, toolkit, and sweater (limited room in my jeep) on top of the amp driving my two subs and have never had a problem.
-Mike