Burning smell

Do you have insurance on these?

What's happening could be an insurance claim that can compensate your blown amp if you're creative enough.

Other than that, I'd strongly recommend not to turn this amp on till you resolve smoking issue. Old saying is that "there's no smoke without fire" The possible source of smoke could be one of those LARGE filter capacitors. They're not active during stand-by. 

Is it unusual for the capacitors to be blown after 6 years ? it looks like that may be the problem

I have homeowners insurance. They are unlikely to cover this

Check if these caps made in China, then you'll probably find answer.

There are also smaller caps that need to be checked around high-heat power supply area where you may see it either out of shape or draining liquid that potentially smokes. Heat damage usually visible

Homeowners insurance will compensate you if you continue to listen to music and burn your house :-)

good one