The Vandy's are a league above the Paradigm's. I use to own a pair of the Studio 40's v2 and I have a buddy that has the 2 Sigs that I listen to about once a week. The Paradigm metal dome tweeter will run you out of the room if not matched with the correct components and/or your room has less than adequate treatments. The Vandy's are better in every aspect other than looks and sensitivity. Vandy's are 86 and 7ohm and the Paradigm's are 91 at 8 ohms. I don't know the spec's of your NAD mono block's but, I would assume they have more than enough to drive the Vandy's. If you do more than 75% HT I would say go with the Paradigms but, if you are looking for the better music speaker, it's a no brainer, go with the Vandy's
Good Luck,
Burton
Good Luck,
Burton