Bel canto problems


Looking for guidance. I have several bel canto 600 ref m amps in a home theater set up. Two of the amps have had intermittent output problems which I ascribe to either overheating in the cabinet or a short internally. One of the amps actually is off more than on. (Btw the amp led is always on)
i have sent amps back to the factory and the problem amp back twice. Bel canto always says they are fine and then the problem starts right back up.
at this stage I would love to get out but the factory does not seem to know or care how to fix the amp (s). The amps were bought q4 2015 and have not worked right in two years. Any suggestions other than cursing the gods would be welcome. I used to be a big bel canto fan but this is pretty bad for amps that are considered high end.
emster
YOU NEED TO REMOVE THE COVERS AND RUN A FAN TO KEEP THEM COOL!!!!!!!

I've had the same issues since I bought them and BC NEVER fixed the problems despite sending the amps back on several occasions.

And they are not in a cabinet but a audio rack with lots of air around it.

BTW, I keep them on all the time.
Heat is an issue and I am experimenting w amps outside the cabinet. Interestingly, the 150s and one of the ref 600 m amps have been fine in the cabinet the entire time.
The 150's and one of the 600's that don't turn off could have a slightly higher temp threshold (Thermistor spec variations) before turning off.

Cheers George
Agree with colander 

which power cord are you using? 
Using any power isolaters? Power Conditioners? Etc 
wall outlet ok? Using the same outlet for other uses that may interfere?
are the impedances b/w amp and preAmp a goood match?
etc etc
I never heard of Bel Canto not stepping up their game to resolve a product defect for a customer. I recommend having a friend test the suspected amp in his system. If he confirms the suspected defect, then get on Bel Canto to resolve the issue. If he can’t confirm the suspected defect (that is, it performs normally as Bel Canto claims), then it’s something about your home theater setup.  
I have two 600m in a cabinet under my Oppo for 6 months and never even turned them off since purchase. So far no problems. They just get warm never hot. Just try swapping them around to help isolate the problem. If one is really bad I can’t believe that Bel Canto would not step up to help you figure it out. Intermittent problems are really a pain sometimes. Good luck.
Besides temp issues, there are two other things to check.

One is the speaker wiring and speaker load. A bad connection, short, or an internal fault in the speakers could be causing the amps to shut down.

The other issue is high frequency oscillation that is out of your range of hearing, but the amp is having to deal with it, causing protection circuits to trigger. The most likely source of this would be one of your source components, a nearby source of RFI, or a poorly shielded or faulty  interconnect. The best way to check is have someone with test equipment check things out in your actual setup. You can also try swapping out or moving equipment (both amps, source & speakers) and see if the problem disappears or moves to new equipment.

Good luck!
I have BC C5i in a cabinet for several years, no problem.

I also have ref1000m amps running fine for years, not in cabinet.

Neither ever heats up much so I would not expect cabinet to be a problem normally.

I bought ref1000m amps used and I found one had a problem with a peeling input stage circuit board. Sent to BC for repair, which they fixed quickly and reliably for a very reasonable price.

Just offering another case for reference. I have no experience with the ref600m amps specifically or BC service in teh last few years, but I have nothing but confidence overall in teh company and products based on experience to-date.
Thanks all. Heat is an issue and I am experimenting w amps outside the cabinet. Interestingly, the 150s and one of the ref 600 m amps have been fine in the cabinet the entire time. 
So I have to think at least one of the ref 600 is defective as it emits sound only around 30 percent of the time. I am disappointed bel canto has not offered to refurbish or swap the amp, they just deny the problem.
@emster  intermittent output problems which I ascribe to either overheating in the cabinet or a short internally.

are the amps warm at all ?        if they are then can you move them out of the cabinets ?
put the good ones in the cabinet to see if they start acting up and if the bad ones get better.
emster"two of the amps have had intermittent output problems which I ascribe to either overheating in the cabinet or a short internally."

What makes you think there is a short circuit in you're amplifiers that is highly unlikely it is much more likely that they are overheating why don't you take them out of the cabinet and/or use a proper fan to cool the amplifiers to prevent this problem but also Bel Canto is known for quality problems but I would check the most obvious problems first before arriving at the difficult conclusion that they are junk and should be discarded.