Diminished sound in left channel

Hi, I've just recently noticed this problem in my system and I'm wondering if anyone can offer advice as to what the problem may be:

After listening to music for a few hours the sound coming out of the left channel of my system is diminished by about 75%. If I turn the amp off for an hour or so everything is back to normal. It's definitely not a problem with the speaker (I've swapped the speakers and the same problem happens). I guess one possibility is the fuse in the amp, but I wanted to get some opinions from the forum before changing them out. I thought that when a fuse goes it's all or nothing and there would be no sound from the affected channel.

My setup is:
JM Lab Electra 926 speakers

Classe CAP-150 integrated Amp connected to a PS Audio Digital Link III DAC via analog coax cables

SqueezeBox v3 connected via a digital cable to the PS Audio DAC

Thanks for any insight anyone can offer.

Looks like some of the output transistors get overheat and having collector voltage emergency cut-off.
Your JM Lab speakers could be the primary culprit (too heavy to drive) your amp having an output transistor problem another words check with the nearest tech and if you can't find one in your area, drop me a note.
Definitely not the fuse. If the fuse of the amp is blown the amp wouldn't power up in the first place. I highly suspect it's the Classe amp although it can be the PS Audio DAC. Try plugging in a spare source such as a DVD player into your Classe amp and see if the imbalance in sound still occurs. If it does, your Classe amp needs a technician.
I think eventuslly, it is going to occur again and will come a point where it is not going to restore itself. You should have it looked at by a technician. I have had a similar problem in the past and it was a blown resistor.
Thanks very much for your responses. It definitely seems to be something with the amp. I didn't mention it in my post, but I have a DVD player connected directly to the amp (by-passing the DAC) and the problem is exists with that component as well. So the DAC can be ruled out.

Before I took it into to a shop I wanted to get some people's opinions about the possibility of it being a fuse (which I could replace myself), but it sounds like the fuse is definitely not the problem.

Marakanetz: I actually have Electra 915's (not 926's) hooked up to this amp so I think the amp should be able to drive them, but I'll confirm that the a the tech when I take the amp in.

Cyclonicman: Was it very expensive to fix the blown resistor you had?

Thanks for all your help, -Scott
Scott, My Rogue 88 amp was still under warranty at the time, so I only paid to ship it for repair.