Higher Efficiency Speakers

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!!!

Have you considered the Rethm Maarga?  

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.

  

I would recommend the SALK Song3 Encore's priced at $6,000.  Jim Salk sells direct and can afford to use the best drivers.  Incredible sound.  They sounded better than a pair of $60,000 speakers I heard at the Rocky Mountain Audio Fest this past October.