A little follow up, I got my amps running last Monday and have found nothing to change my opinion thus far.
There isn't a lot to say about the sound, they seem to just get out of the way, in a good way that is, they just allow the music to flow. I did have the opportunity for a comparison today, a friend brought over his Luxman M-600, a 30WPC class A amp. I've heard the Luxman before in my system and his and it's always been rich though I found it lacking in the perceived speed and extension compared my Atma-Sphere. Swapping in the Luxman for the NC400 was a surprise in a few ways. It sounded rather compressed and muddled in comparison and the biggest surprised was the harmonic richness, where we both expected the Luxman to shine, was actually better with the NCore. Swapping the amps back made the differences even clearer, there was just more musical information with the Hypex amps.
Both were run in balanced mode, same cables, stand and everything else, just the amps were changed.
While I'm sure the little NC isn't for everyone, I'm all smiles every time I listen to music. Played some Bob Marley on vinyl Friday night, never heard it like that before, had to play side two a second time just because I enjoyed it so much.
Looking forward to George's comments on how it drives a harder load than what I have.
mike