A list of efficient speakers at ~$5K a pair.

Hey @mesch is there anything else about the next pair of speakers you'd like to try or venture into that you've not tried prior?  i.e. baffle size, driver configuration, etc. 

For example one of our members here has demoed (narrow baffle) small bookshelf (2-way) and then ventured in to floor stander (3-way) speakers, also owns the Fritz. I walked through some the journey with him. During that journey, I also suggested trying wider front (wide baffle) speakers next for a different type of sound with his next set of slightly more efficient speakers. This is in progress now.  Maybe he'll chime in later on down the road. 

For example, with the builds I've done,  spent quite a bit of time with 2-ways with TW, various tweeter and woofer types. I then decided a few decades ago I kinda liked the sound of WTW, or some refer to it as MTM configuration. I position the tweeter (AMT or Ribbon) at ear level in my seated position. This might be more suitable for lower efficiency speakers and listening preferences. For example, my current custom speakers are 92.5 6ohm in MTM driver configuration. Sometimes MTM can be too much of a good thing for some people's listening preferences yet I tend to be a low-midrange freak so I love this with tube amps.  Will stop there. Best of luck.  

meanwhile,

totally ignoring your requirements, I might pick this for you, I’d sure like to hear it, maybe fit your room, maybe not, seller says too big for his space

Sanders Sound 10E

absolute sound review

A  friend of mine has a pair of Living Voice speakers, I think maybe older R25's?  He got them for a steal price because of some small dings in the cabinets, but they can be had for less than $5K.  You'll pry my old ProAc Response 2's out my of cold, dead hands, but I found these to be very similar in having excellent imaging and a vivid midrange.  In fact, he bought them to replace his own ProAc Response 2's so he could run single-ended amps.  He listens to more contemporary music than I do, and they did very well with that but also classical and jazz.  I really enjoyed listening to them for two days, and if I had the money I would even consider replacing my ProAcs.

@elliottbnewcombjr yeah that is the opposite direction, the Sanders 10E site shows they like to pair them up with a powerhouse 500w-900w Magtec Class AB amplifier.

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Other:

My local dealer has Soundlabspeakers, and I’ve heard the Majestic 545px 8ohm speakers driven with my same Quicksilver 60-100wpc tube amps and they sound glorious too. Lower efficiency and 8ohms, yet the tube amps do okay with them fwiw. https://www.soundlabspeakers.com/majestic/

Actually he’s had the super large 945 units there and drove them with my same QS Mono 120 tube amps without issue, with the higher 8ohm impedance. I like the size of the shorter 545s with wider front size.

Would the OP go for these, who knows ;). Neither of these are "efficient" though, not even close. Not efficient. Tube amp capable, maybe

Arendal 1723's are 92 db and sound great.  Certified THX Ultra.  HDF cabinet.