amp dies in middle of playing

I have an old adcom amp that occasionally dies whenever i play bass heavy passages at high volume. This is a new problem as the amp used to drive to far higher levels with no problems. The way it happens is ill be playing a rock song at loud but not rediculous volume, like 11 on my preamp and the music will cut off and then come back on after the amp protection circut turns back off. I think its a power supply problem but any suggestions would be greatly appreciated.