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
I am doing a similar search. Take a look at Audio Note AN-E. Large range of prices. Maybe problematic for your room due to the fact that they prefer to be placed in corners.
Magico A3s, Focal Kanta 2s, Joseph Audio, Harbeth 30.2, Spendor D9.

Your head will be spinning but OH what a ride!!!
Recently, at the Capital Audiofest, outside of Washington DC, I heard some remarkable, very high efficiency speakers made by Charney Audio.  The system I heard cost $17,000, but, they do make cheaper as well as more expensive systems.  They, like many high efficiency systems, sound particularly good at lower volume levels and would be very good in a small room (the room at the show was small).  I liked the Charney speakers I heard at the show enough to be considering them even though they cost a fraction of what I currently run.

I have also heard, and liked, Rethm speakers and the Tekton speakers that are also reasonably efficient.

Do you have any hum or other noise issues with the M-60?  Every one of them that I heard had a very slight hum.  This hum would be more pronounced with high efficiency speakers, particularly if you will be sitting close to the speakers in a small room.  That would be another issue to consider when going with higher efficiency.