speaker upgrade fever

I'm considering a speaker upgrade to compliment my Aesthetix Mimas integrated. Currently, I've got KEF Ref 1 monitors paired with (2) REL S/3 subs. Must stay away from bright, analytical and clinical presentation. Room size 12'x19'. Music is jazz, acoustic Americana, Chamber, symphonic etc. 

Looking at the ProAc K1, Triangle Duetto and the DeVore o/baby. Also, a huge departure, Vandersteen Treo CT, floor standers. I understand Vandersteen pairs well with the Mimas.

Always open to suggestions, happy to buy quality used and demo.

Budget, ~$8-$11K