Beware of NAD M3 Fire Hazard

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

Odd the AC line safety fuse did not blow.

@jea48, Jim, I took a look at the service manual for the M3, which can be seen at hifiengine.com if one is registered there. It appears that it has three fuses, all of which are AFTER an EMI filter, consisting of inductors and capacitors, which is connected between the incoming AC and the rest of the amp.

There are two 5 amp fuses (assuming this is a 120 volt model), one for each channel, with the main (rear panel) power switch connected between the filter and these fuses. There is also a 100 ma fuse protecting standby-related circuitry, with a relay connected between the filter and this fuse.

All of the fuses are located inside the unit, and they are not accessible on the rear panel.

All of this would seem to cast suspicion on the EMI filter as the culprit, although secondary damage elsewhere within the unit certainly may have occurred.

Best regards,
-- Al

Did the service manual indicate the correct fuse direction? Might have been switched.

Thanks for the responses. As far as I know the fuses are intact. I stopped the sparks shooting out the top by unplugging it. I took it to the NAD authorized repair facility and they said a faulty power supply caused the round cylinder ( not sure of part name) to explode which probably damaged the board and other parts. I can send pics if anyone wants to see the damage. Thanks.

Safety caps do fail short, not enough though to create a fault condition a fuse or breaker can clear. RIFA caps in old Mark Levinson gear are notorious for this. 

If it's the "round cylinder", it is possible that something conductive shorted the power supply cap or caused a voltage reversal. Who knows,  a discarded component lead was dropped inside the unit during production and wiggled its way to a bad spot during shipping/setup.