2.0 Stereo speakers on a $2000 budget?

Magnepan MMGs run $600 pair
SVS sells a pair of 12" sealed subs for $1,000

Your NAD will IIRC allow you to cross the subs at line level and the power output should be adequate for highish (tho not crushing) SPLs in that room.  Very high SQ and full range reproduction for less than $2,000

No one on this site has any idea what you will like personally. Basically we recommend stuff we ourselves liked and that's about as far as it goes. So many to choose from, don't take our word for any of this, just way too many variables in my modest opinion. In the end it's a crapshoot as you cant A/B audition all of them in your home anyway. 2K will get you some great sound so dont sweat it too much

Have you heard the kef ls 50?

So, what speakers have you been using?  What are you looking to improve upon or what sonic properties of speakers and music reproduction are most important to you (i.e. Micro/macro dynamics, tonality, timing, imaging/soundstaging, etc.)?  This info would help greatly in making more targeted recommendations. 

The ProAc jumps out at me right away as interesting choice.

speakers I have heard and liked with that NAD amp or close relative:

-Vandersteen 1c
Dynaudio Audience (82 and 122 both available now on Agon used)
-B&W 683 S2
-Focal Chorus 726

note these are all very different sounding speakers but had their charms with NAD power.

other intriguing suggestions mentioned in this thread that I have heard but not with your NAD amp:

-Monitor Audio Silver 8 (Full Disclosure I own some MA speakers now and like them a lot)
-PSB Imagine tower
-Magnepan MMG's plus SVS subs (very intriguing idea)

for that matter, SVS sub(s) with any synergistic stand mount speaker like B&W CM-5, Monitor Audio Silver S2, KEF LS50, Dynaudio Excite X18, others?

There are some Revel Perfoma F32's on Agon now for $2K which strikes me as a good deal, but not sure of match with your NAD amp.

A suggestion on the NAD no matter what speakers you end up with, scrap the stock metal jumpers between the Preamp "out" and power amp "in" on the back, and replace them with decent 0.5m interconnects. Might even help tame Klipsch's treble a bit.