Higher Efficiency Speakers


I am going to start my quest for speakers. My room is 13.5x13.5 but open on two sides... so not an ideal space. But never the less this is what I have to deal with.  I have a set of Vandersteen 2ce Sig ii but would like to upgrade. Was thinking about something horn. But seems when you go that route it gets way out of my price range.  Thought maybe look around for some Used Vandersteen Quattro CT but budget starts to stretch at that point. Like to stay under $10,000. What would be good speakers to look for to demo? If my room was alittle bigger.  I’d almost go the other way, and look at Small Maggie’s and Monostrap my amps.
System
Atma-sphere M60
Atma-sphere UV-1 ( Probably the most Modded. Will be at the end of the month. Lol) 
Bel Canto Dac

128x128pstores
Another shout out for Charney Audio! I have a pair of Maestro's with the Omega RS7 driver ($5,400) in my 11x15x8 room. Sensitivity is 100db so low powered SET amps are the way to go. I have ANK Interstage 8w300b amps and can't get enough of what this combo can do. In the room performers, drawing you into a deep, wide, and engaging soundscape. If your within a couple hour drive to Central NJ make an appointment with Brian. Very well worth the experience!
http://charneyaudio.com/
@rodge827 - Those speakers look great! I use Omega HO with a SET amp and it's magical. How does the sensitivity increase w the Charney utilizing the Omegas RS7 driver vs an Omega with the RS7 driver? I am genuinely curious. 
I got the sensitivity number from the Charney website...I think it has something to with the horn design. There is very little resistance from back waves in the chamber and the tractrix design of the horn. Just a guess, Charney could better explain it. I have owned a few Omega designs and the RS7 shines in the Charney horn. Very low excursion hard to see the driver move during play back.