Might be heat issue? I noticed the lower-end models are very reliable. Bihira that you hear about someone with a C326 having problems. My C316 I used as a home sound system amp before and was running almost 24/7 for over two years with no problems.
My C372 though would get extremely hot, to the point where I'm not comfortable using it outside an air conditioned room. It also developed issues after a while. Crackle in the left channel, stiff like that. Still with me but I've had it repaired twice already in the course of owning it 5 years.
I had a bad experience with the NAD C325BEE amp with one channel cutting out and tried to have it repaired at the authorized service center at a high cost and the issue came back in a few months.
I really like the NAD sound so I replaced the 325 with the 326 then I placed a computer fan on top of the hottest area of the top case grill of the 2nd NAD amp to mitigate the potential reliability issues from overheating. After about 3 years, the amp started entering to standby-mode on its own intermittently even when music is playing. I didn't bother to have it repaired this time and sold it cheap as a defective unit.
At that point, I gave up on separates after that and went with the KEF LS50W active speakers. Three-and-a-half years later, still no issues with the hardware.
Is it true that the C325bee and the C326bee have fully discrete circuitry (no ICs) and that some of the components used were of the cheap kind to keep the costs down and may have more points of failure but are easier to repair? I recall reading that in an audio forum before.