Over the years I've owned several NAD components, back to the 1980's and have had minimal problems with the brand. A receiver I bought years ago had that same problem (one channel suddenly about 25% of the volume of the other), and my M5 Masters Series SACD player had a transport failure (wouldn't open the tray), but other than that, good service from NAD components.
Having said that, I understand that NAD was one of the first audio companies to outsource their manufacturing to "contract" builders. It would not surprise me that, if you opened two of the same model that the components would be from different suppliers.
I have since upgraded to electronics designed and built in the USA (McIntosh & PS Audio)...and so far (knock on wood), haven't had service issues with either brand.
Having said that, I understand that NAD was one of the first audio companies to outsource their manufacturing to "contract" builders. It would not surprise me that, if you opened two of the same model that the components would be from different suppliers.
I have since upgraded to electronics designed and built in the USA (McIntosh & PS Audio)...and so far (knock on wood), haven't had service issues with either brand.