Yamaha C-60 problem

Last night the fam was out so I decided to take my system for a loud walk. A few minutes into having it cranked to about 90% the audio got very muffled sounding with no bass for a few seconds then it came back for a few seconds then it happened again. I shut everything down and noticed my C-60 was very hot and has a faint electronics burning smell. When I turned it back on it sounded just fine and has been fine since. Maybe the heat and the smell is normal but I would like to know what caused this issue. I took the top and bottom off of it and I can't see anything burned. The C-60 is hooked to MX-630 amp into Infinity Reference Six speakers. I was listening to a cd I know is perfect. Does anyone have any ideas where I should start?

A few minutes into having it cranked to about 90%

Click to expand...

Clipping ?

I'm not sure but I don't think so. It sounds fine now and it hasn't happened again. It's possible the bass response may even be better since that happened...or it could be in my head who knows? Maybe the slight smell is normal and I'm concerned about nothing, I know the Yamaha preamps run hot anyway.

Strange... Maybe a cold solder connection or dirty switch.