I did audition the 773 at a store. Lots of power, liked it.
I'll likely pick the T763, with less fans, a toroidal tranformer like the 773, and enough power for me. The Y 4600 was also on my list, but
I'm leaning toward the NAD because I like Music first
and heard from a couple people - including JC here,
that NAD would have an edge on Music.
I don't plan to use any EQ features
nor special DSP modes besides standard Dolby/DTSes.
AND I only have 5.1 speakers. No way my wife will accept
more than that... i'm happy i went this far already :-)

I also found that I would be able to control/setup the T763
through the serial port from the Media Center PC in the living room. Just download the Windows app from NAD.
Nice... I can already see how setup will go even faster than with the remote and OSD... now that's a nice feature for a PC folk like me.