Floor Standing Speakers That Would Sound Good With the NAD Integrated Amplifier.

I had a prior model in my prior "B" system. The C370 integrated, so I will comment on the bespoke NAD sonic signature from personal experience..... not just its strengths but also Its warts.

I heartily agree with the common themes in published reviews .... sample attached

http://www.techradar.com/reviews/audio-visual/hi-fi-and-audio/amplifiers/nad-c375bee-625300/review

AGAINST

-- Slight softness in midband
-- Lacks the polish to make the most of some high resolution speakers

I would not spend anymore on speakers than its max MSRP (past ) $1500 price-point (this model now discontinued ) simply because it planes out dramatically in its audio performance capability with speakers capped to its price strata,

IMO and my hands-on experience , doubling your speaker budget with this rig to $3K won’t help you.
As a personal experience comparison, I ran TOTEM ARROS and FORESTS simultaneously with the C370 . The FORESTS at more than double the price of the ARROS did not prevail at all.

In fact, I actually preferred the ARROs simply because it was a better match (for me) because of the "dark" and rolled-off top end audio signature of the NAD.

The FORESTs then mated with an ARCAM FMJ rig (much more $ inline with the FOREST price strata ) with a better detailed and airy sonic signature was the key to an audio performance step -up that the NAD could not deliver on.

Your takeaway IMO

I agree with Willand’s posted suggestion that the PSB speaker line (same distributor) will marry up much better with the NAD

FWIW

I completely agree with akg_ca in that with certain gear, particularly in the mid-hifi range, you'll reach a point of diminishing return when choosing speakers. I've experienced that with a couple of integrated amplifiers that I've owned in the < $1500 range and experimented with my own and friends' speakers, some of which were an order of magnitude more expensive than my integrated. They just sounded different and in some case better but not necessarily jaw dropping better. I must admit there was one exception and that was when I hooked it up to a pair of Charney Alerion single driver horn loaded speakers a friend of mine used to own and it simply blew me away. So I guess extra efficient speakers might not follow this logic. If it were me, I would reconsider my budget and audition as many speakers as possible before making a decision.

What's your ultimate system goal? Are you married to your NAD?

Personally, it's aways worked better for me to choose speakers I love in my price range and that work in my room, THEN find the amp that best mates with the speakers. (Yes, I think you should fall in love with your speakers - otherwise, why bring them home?) I am the patient sort, willing to wait to upgrade to get optimal sound. I've never had the budget for an "I want it all and I want it now" system. 

And that's the thing - it's a *system*, and synergy is important.  The speakers have always been my key investment and were allotted the largest slice of my budget, followed by front end (be it digital and/or analog), then amp, then cabling  etc (and that's a whole 'nother subject). 

I'm totally onboard with integrated amps, There are some truly outstanding ones available in various price ranges - it's like a golden age of integrateds, be they they SS, tubed or hybrid. Once upon a time, I had relatively expensive speakers and separates and loved them. But I am very happy now with an integrated amp and plan to stay that route.

Your NAD may not be not the last word in transparency or upper frequency refinement but it's quite enjoyable at its price point and capable of driving a wide variety of speakers. Consider auditioning reasonably efficient speakers in the $1500-$2500 range, enjoy them with your NAD for awhile, and - if you feel the need - put the money saved toward trading up your amp based on your new speakers. Also consider buying used/demo amp for bang for buck.

You don't say what you're looking for in a speaker or your music preferences other than full range and compatible with your NAD. But I concur with the above suggestion for Vandersteen 2s and would add the GoldenEar Triton line to that list (caveat: we have the Triton 3+, $2500.) I'm a big fan of full range or as close as you can get.  You hopefully have local dealers where you can audition both full range and stand mounts - you may even be able to bring your NAD to try with them. Don't be in a hurry and have fun. But get out there and listen.

My personal experience is that I have an Nad C-388 integrated amp and I'm using a pair of Qacoustics Concept 40 floorstanding speakers and the combination is great. Great detail, tight bass and they are only $999 for the pair. Qacoustics put out some great sounding speakers for a very reasonable price. The build quality and gelcore technology they use makes for a distortion and vibration free speaker. You can't beat British sound, imo

I had a NAD  C356BEE and C272 power amp that was bi-amping a pair of PSB T6 towers- new model equivalent would be PSB X2T.  
Deep and impactful bass- the bass response on those PSB speakers is incredible and your amp will deliver the goods.  Midrange was excellent- a little forward but excellent with vocals and jazz.  The upper frequencies were again- quite excellent.  PSB tunes their titanium tweeters to sound incredibly detailed and yet natural.  No subwoofer required.