Best speakers under $500? Fire away!

seriously, the Gallo CL2's I bought are still breaking in and have detail, accuracy, spaciousness and natural tone that will put many of these suggestions to shame. They are 90db and a transmission line - the bass is extended and accurate, you can actually hear the tone and articulation of the bass, not just boom like the B6. I heard them up against the B&W 685 mentioned above - the Gallos are in a whole different league for sure. That CDT tweeter and crossoverless design is special. Call Dan at Gallo!!!

One other option is a used pair of Tekton Lore Reference - They can be had about $500. Very efficient, huge effortless dynamics and soundstage. 

I see you went with the B6. I think this a mistake based on your amp - they are overly warm, (rolled off really) and very bass heavy (boomy) unless you have a room that is very well treated or can move them into the room about 4 feet, no kidding. I feel like NAD will only exacerbate these issues. B6 would be best match with very accurate and neutral electronics, even on the slightly lean side. good luck.

+1
I agree the Elac is a huge mistake.

+2

But this is what happens when someone insists on asking for suggestions on the internet, especially speakers.  Instead of making up a short list and going out and audition.  You end up buying what the popular flavor of the year is from a consensus from a bunch of strangers on the internet.  Which seldom ends up being the right speaker for you.

If the OP had asked a year ago, it would have overwhelming been the Pioneer SP-BS22 LR.  This year Elac.  Who know which one next year.  But you can be assured the question will continue to be asked.