I spent the week with the nad and I must say it sounds very nice!, setup is fairly easy and the layout on the back of the unit is similar to my D2 except the nad has no balanced connections and some other minor things. I did not have the ability to blind test nor do I have the desire to I was just curious of the sound and wanted to listen to it. I think the mc15hd has a bit warmer sound compared to my D2, I do prefer the sound of my D2 in my system it sounds a bit cleaner and more natural sounding especially with dialouge. When I bought my focals I found heavenly sound paired up with my D2 and nad m25 amp the center is spectacular to me. The nad is pretty tweak able but with the d2 you can tweak until the cows come home, I also love the the flexibility of the genum vidieo processor.
bottom line is if I was in the market for an ssp Im not sure I would spend the extra 3 or 4k on the D2. The nad is a great value piece and I definitely would recommend the nad mc15hd, it sounds great and priced right, audessy is a plus too!