Best high-efficiency speaker under 10K

Musicfile,
Yes, they are clearly some of my favorites

I forgot to mention the Audio Note earlier...I have owned the ANE/SEC silvers and they are terrific speakers as well.

Keep in mind that AudioNotes were designed to work in the corners of your room, if that's an issue for you...
Will Tonian appear at RMAF anyone?

Assuming that 96 dB meets your definition of 'high efficiency', I would strongly suggest that you look into Duke LeJeune's Audiokinesis speakers. I own his Planetarium Betas, and have found them to be quite extraordinary. The Swarm system DOES take up space, so if your listening room is tight and/or you're not willing to have 4 small boxes scattered about, you should look elsewhere. I am assuming that his slightly lower efficiency speakers such as the Jazz Modules (92 dB, $4500) are not efficient enough. If I'm mistaken in that assumption, they might make a great choice. Good luck!

I am assuming that his slightly lower efficiency speakers such as the Jazz Modules (92 dB, $4500) are not efficient enough.

That would depend on the size of the room and how loud the OP listens. I have a small room, listen to the same type of music as the OP (sans the opera), and at levels that don't exceed 90 SPL very often. I have an 8 watt SET amp that drives the Jazz Module nicely and auditioned a 10 watt solid state amp that had no problem driving them either. So a 13 watt EAR, which will play more like 8 or 9 watts with the 12 ohm Jazz Module should do fine. IMO, I think Duke understates the efficiency of his speakers. I much prefer the Jazz Module to the Planetarium series too, but that's just me.

The Tonian Lab speakers are phenomenal as well. I have the TL-D1 ($2500 these days) which is pretty much an entry level model. I can only imagine how good the upper end models sound. They do produce a lot of detail though and are extremely transparent. Not everyone's cup of tea in that respect. I doubt Tony or his speakers will be at RMAF. However, I did ask him once about a home audition and he offered 7 days with only shipping charges as my risk. If you contact Duke at Audiokinesis he will work with you as well to see if he can get you a home audition. He personally drove two pairs of speakers to my home and allowed me to listen to them before buying.

Along the lines of my earlier comment, imo the most important factor in determining the necessary speaker sensitivity is the dynamic range of the music being listened to. Meaning the difference in volume between the loudest notes and the softest notes, or perhaps more appropriately in many cases, the difference in volume between the loudest notes and the average note.

For well recorded, minimally compressed, classical symphonic music, particularly on audiophile-oriented labels, based on my experience 95db/1W/1m would be an absolute minimum requirement with a 13W amplifier, with several db more than that being preferable. For most other kinds of recordings, and at typical listening distances, considerably less than that would be acceptable.

Keep in mind that a dynamic range of 30db, which is easily reached by many classical recordings, means that the loudest notes will require 1000 times as much power as the softest notes.

Regards,
-- Al