"Absolute best" used speaker for $8-10K

Is the B&W 802D not better than the 800N? I have not compared the two but the 802D with the diamond tweeter has to be heard before buying something else. I agree with the reviews which say the highs come from a perfectly black background and match the mids perfectly, below that the speaker is a little warm (IMO) but certainly worth a listen.

I have to stand behind trcnetmsncom. For 10k you should be able to get a good pair of used Eidelons, they do everything you're looking for, really well, if you have the right gear to go with them.

Not one of my personal favorites but given your stated preferences I would suggest the Theil CS6

Merlin VSM-MX! You would be doing yourself a disservice not to consider them, they have all the qualities you are looking for!