I don't see any real advantage to switching from your NAD M-15 to the Emo unit except for the decoding of DTS-HDMA and Dolby True-HD.
The main reason is the hdmi switching, which I have a hdmi switcher for but the integration would be so much better and easier for my family to deal with also. But like I said not at the expense of sound quality. And as far as the uncompressed formats I'm using 7.1 analog audio through my bluray player, which I would still use because I prefer the analog audio over the digital audio. I also have a logitec remote and it gets me through but it still has some quirks. So basically I'm wanting to know if there is a major difference is the sound quality of these two or are they on par with each other?
I can't speak for the Emotiva but I am using the NAD M15's brother pre/pro the T175HD and I don't think I could be more pleased with the sound quality. Very open soundstage with plenty of depth and a slight warmness while retaining spot on detail. The T175HD can still be had(refurbished) for $1599.00 at Spearit Sound.