Since my Kef LS-50s were still boxed up after their field trip to Tom Brennan's place, and since I was cleaning out one of my closets, I decided to pull the Quad 63pros out, and see how the NAD fared with a more full-range speaker, particularly one that the best amp here, the Pass Aleph 30, could properly drive. Basically an assemblage of what I consider to be the best three components here.
The results?
I've not heard better. Certainly not here. I've heard different, but there are things this combination does that I've not heard extremely expensive setups do as well (to my ears, anyway). Perfectly balanced, lively, dynamic (yes, the Aleph eeks a good deal of bass out of these 63s, the pros being a more robust/rigid speaker than the original ESL-63), with an openness and clarity without going overboard with the hi-fi exaggeration of detail. I always forget just how good the Quad 63 is. Cabling was Straightwire Crescendo between the NAD and Aleph, and Vertere D-Fi speaker cable (which I have to say, has made me a cable convert. Sorry to anybody offended by such things

).
I might keep this setup until I hear about the T+A amp. Or I might not (the 63s take up a lot of room in my bedroom). Either way, I'm going to spend a lot of time listening while they're setup like this, and I'm going to remember this if I move apartments in the spring, as a listening room where I could leave this up permanently would be very very nice.
Anyway, in a setup with speakers that will tax a preamp and expose it for what it truly is, the Quads have revealed the NAD M-51 to be top-shelf.