Issue with Mc 5200 Amp shutting down...

Thanks in advance and know that I am as far from technical as can be-so please be simple in ideas or questions?...in a nutshell, I have a Mc5200 amp that shuts down (powers to black) after about 15 minutes of playing...will restart but repeats behavior...entire system is as follows...but this happens when no components are playing -only Sonus radio etc...
McC26 preamp
NAD 7130 Rec
Mc MA 5200 amp
b/o and transcriptor skeleton turntables
Rega CD
Bose Satellite Speakers
Klipsch Heresy Speakers  

the NAD runs the Bose -no problem
the 5200 runs the Klipsch-there is the problem...

so even when no components playing-only listening to Sonus and LOW Vol, the Klipschs crap out after about 15 minutes of playing...power button brings it back but only to have it repeat again...bought the amp used but minty...so I dont think that I am testing the limits of the amp or driving to hard, connections seem good-no special cable or anything else...ideas please???