I had an Innersound amp completely melt down. Luckily it was in a pretty heavy chassis so the fire stayed inside and didn't burn my house down. Innersound was out of business so no recourse but on something like that NAD should just get you set up with a new amp, doesn't matter if it's in warranty or if you bought it used. That should not happen and if it does they should cover it, they are a big company. Let us know what they say.
Beware of NAD M3 Fire Hazard
My $3k NAD M3 started shooting sparks out the top and burned the shelf that was 8" above. Luckily I was home and not sleeping or the house would have burned down. If anyone has one of these I advise them to unplug it when not in use. I took it to two different repair shops and they said it would be about $800 to just get it running and there may be board issues. They advised not to take the gamble. Anyone have any suggestions on what to do with it?