I have the NAD M3 and right before this I owned a Wyred4Sound STI-500. My speakers are power loving Usher BE-718 monitors similar to your speakers. The NAD is (for me) much more satisfying for my taste and system synergy. It also has the outstanding feature of a variable high pass filter on one set of pre-outs so I can integrate my pair of subwoofers with the Ushers. If you currently do or plan to use a sub in the future this feature is pretty unique and absolutely effective.
Now I can fully crank electronica like Underworld or Crystal Method and the Usher woofers don't look like they're going to fly out of their frames while the pair of JL subs get to have a field day and go crazy. Really refined too on folk, jazz , classical, and most everything.
The W4S more extroverted-wider and deeper soundstage, more upfront detail across the freq spectrum, and outstanding separation of instruments. Just phenomenal with the right recordings. Unfortunately with the Ushers it was beamy, metallic, and uncomfortable sometimes as well. The M3 is meatier overall, much more forgiving of bad recordings, never quite phenomenal but always really good and doesn't leave me wanting. The other nice thing about the M3 is that the louder you play it the better it sounds. It gets fuller and stronger without getting more forward.
I haven't heard your speakers but if they are laid back the W4S is a great recommendation. If they are a bit forward the M3 is a good alternative. They both have high-quality stepped attenuators which I have convinced myself is a great feature. That's my two cents' worth after I read the good recommendations above.