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
These will give me something’s to look at. The NSMT’s I already drew a line through. As with the KLipsch. Since I had owned most of the Classics from Chorus II through the Khorns. I’ll do alittle digging on the rest. Appreciate the responses. I am also considering Audio Classic Loudspeakers. Except one from there low end. 
I have Maggies and Love rhem, but I might look at high efficiency speakers in a do over.

I would love to try a tube amp as I have a tube pre amp.  However, Maggies require Lots of current and that removed the tube amps from consideration at my budget point.

Enjoy the journey and ket us know where you end up.
I have my Vandy Treo's at near mid-room (between LR and DR 12x24x8).
I have excellent soundstage and reproduction with a pair of 2wq subs.
I owned the 3a sigs and went up to the Treo's. No comparison, everything is much more coherent/ seamless.
I also own Ralph's MA-1's/MP-3, as well as Ayre MX-R's.
Both amps are beyond what I thought I could imagine/afford.
I would ask Ralph is the M-60's could power Treo's-If you got the 2wq subs, I think it might work. And, you'd be 85-90% close to a Quatro.
Bob