Got it in my system. When I first put it in it was dead silent, the black level was amazing. Then I remembered I forgot to turn it on. After I turned it on, it was still dead silent. Then I hit play and only had music from one speaker. After realizing I forgot to flip the switch from RCA to XLR on one input, I had both channels.
It works well. I really like the adjustable gain. I have set at the lowest gain (19db) which works great with my RME DAC which puts out 19dbu with 6dbu headroom (so at -1db on the RME with a full digital signal it will just hit clipping on the amp). My calibration level is 78dbc for each speaker at -20dbfs which puts me at -11db on the RME with this gain. I use music leveling set to -20dbfs, so most albums are turned down. Even cranked way up for me I am unlikely to get within 6 db of clipping (which is a lot more headroom than my Maggies had which were about 6db less efficient).
The only thing I am not thrilled about is mine is one that was made before NAD incorporated a turn on sensor so it would self power on with music. I shouldn't complain, I paid $1550 shipped to my door from the seller.