I used to own an M3/M4/M5 and had a similar problem. I returned the (two week old) unit to my dealer and they did some sort of software update which solved that problem.
In the past I've owned several NAD components and have found they just need repairs, not enough to abandon the brand, but nearly every NAD component I purchased needed repair.
In the past I've owned several NAD components and have found they just need repairs, not enough to abandon the brand, but nearly every NAD component I purchased needed repair.