Ok the coustic amp is cutting off... Let me explain... My head unit has a crossover for the sub amp .. It is set to 63hz +1.. ( Pioneer deh-p2900mp)

When I put the amp on low pass it plays great and sounds good for a while the it just stops playing bass..it gets a little hot , the protect light does not come on or anything... However if i live the amp in normal pass mode it plays just fine at all volumes but I do get some distortion thru the sub as I believe that some mid bass signals are making it to the sub,,

I guess the real thing to do would be to buy a mono amp..