Beware of NAD M3 Fire Hazard

but even if a shorted rectifier allowed AC on the cap without shorting out the power transformer's winding, downstream caps might be just fine as resistors are in the circuit that could have limited current.

Yeah, but that pic man, it shows sprayed cap juice everywhere.

I won't derail the thread, but .... this is the perfect example of why you should never remove the ground pin on an AC plug.

Failures are rare but they do happen.

This case wasn't probably caused by a bad ground pin, but this kind of failure can happen and you want the chassis to be grounded by a big beefy conductor when it does.

I haven’t seen capacitor application notes in decades, but I believe heat still applies, right? That is, the capacitor can be aged while on, not necessarily because of the voltage applied but because of the heat in the amp. Further, higher temperature caps also have longer life spans at a given temperature than lower temp caps, or am I mistaken?

I agree, unfortunately, that the failure here seems not worth fixing. That’s a lot of cleaning to do, with no guarantees.

If it were MY personal unit, I would attempt to clean it, and see if the remaining power supply works, and if the logic/preamp circuits appear in tact, then and only then would I attempt to rebuild the burned out side. Still, lots of work with no guaranteed happy ending.

Take a look at the inside picture here:

https://hometheaterhifi.com/reviews/amplifier/integrated-amplifiers/nad-m3-integrated-stereo-amplifi...

The two round metal covers at the bottom are on top of the transformer.  The next 4 round can things above are capacitors.  Just curious which one.

pwb --- The tall round can like things or the donut like things??

Have you removed the ground pin?
If not, check that your socket is correctly wired.