let's say that you are lissening about helf an hour to the first amplifier, the nad c352 ,and after this to the audio.c. azur 640a.
and you lissening to the music not in loud volume, but anough to hearing all the bit and the sound from the music.
and you leave the tone control (direct switch is on). which of them have an equrate an dynamic balance between bass and the treble? so which of them could sound better in , lets say "low" volume level - 25 - 30 watt ?
I don't want to be a pain in the *ss, but that's for you to decide. Listen to both of 'em.
Personaly I would go for the cambridge, I've listened to the Azur 540 and I find cambridge very involving, and in you face, dynamic but also less detailed, so you have listen to what you prefer. however I haven't really listened to the NAD. I know that it's quite difficult to look for the right amp. Just listen to many, use the same music (the music you like) and listen, listen and listen some more. I recently bought the NAIM NAIT 5, which I'm more and more love.