John, if this was the case then the OP would not be having issues with his amps shutting down after 15 min...

I am not saying that the amps do not put out the power that they are advertised to do so... just that for a longer duration they do not have the cooling capacity to maintain that output... the OP is hitting the performance wall of these amps, which is why i was recommending finding a better cooling option if he wanted to keep his amps instead of buying different amps..