NAD C275BEE break in period?

I've been doing 2 sessions a day of 4 hours+ when possible.  You don't need high volume levels.

I had the C375BEE, BTW, and it clashed with my Totem Acoustic Rainmakers.  There was little in the way of a sweet midrange, at least in my case.  These NAD amps have a different approach that sees no increase in power going from 8 to 4 ohms, and I always wondered if that was why it sounded off with the 4 ohm Rainmakers.

Arcam is definitely in another class.

Not sure about that.  Totem Acoustics, for example, recommends 100 hours or more of easy going on many of their speakers to break them in.

I tried turning up a sub of theirs that I acquired, and it started making mechanical noises.  After break in, it was fine.