Speaker shootout update; aggressive treble eliminating some (fairly?)

I've been trying out speakers in a complicated shoot out, both bookshelves and towers — all in my home with my gear. I'm looking for speakers obtainable up to about $4k but could go up (or down) a bit if the right thing came along.

Basic facts: All speakers were run in at least 100 hours. Room is 27 x 14 x 6.5 ceilings. Powering with all QS tubes, 60w, NOS, tube R2R dac, and decent cables. No terrible reflection points; room not overly live or dampened. REL R 328 sub available but I did most listening without it.

Recent auditions, type:

Klipsch RP 600-M (budget singleton of the group)
Fritz Rev Carbon 7 mk II (bookshelf, 2 way, soft dome)
Focal 936 (tower, 3 way, inverted metal)
Martin Logan Motion 60s XTi (tower, 3 way, AMT)

Coming soon:

Salk SS 6M (bookshelf, 2 way, beryllium)
Dynaudio Evoke 30's (tower, 3 way, soft dome)

Let me speak just to the problems, rather than what was good about the speakers. So far, I've found the Klipsch, Focal, and especially the Martin Logans were all too bright — forward, aggressive, "turn it down" treble.

The ML's were the most impossible to tame and hardest to listen to on more tracks. (I did a lot of hanging of towels and other dampeners and other soft things to try to see if I could bring them to heel. I varied the recordings used. Changed cables/wires. No luck.)

The Focals were occasionally too bright; their bigger problem was a bit too much energy in my small listening space. They were better when I plugged their ports with socks.

I'm looking forward to how the next two speakers sound. The Dynaudio towers, I notice, are 10 inches shorter and half the weight of the other towers; not sure what that might mean, but it could just be right size for my space. I'm looking forward to seeing if the Salks bring more detail to the treble without also being too rolled off or harsh.

Hearing is very personal for physiological and taste reasons. However, if anyone has any thoughts about why I might be experiencing some of the phenomena I am (harsh treble, especially) based on my room or gear, etc., that might help me understand factors I'm not fully appreciating. Thanks.

Not sure what equipment you are using but IMO that is where the brightness is coming from.  The speakers are just reproducing what they are being feed upstream.  Forget the cables and room treatments, they may be a small part of the problem but if all of the speakers are reproducing the same issue then IMO it is your equipment.

Happy Listening.
Trying to help and chatting with Hilde45, here is what I’ve gathered since his speaker demo startup. May help for anyone assisting to analyze the gaps and opportunities. Hopefully these notes (or assumptions) might save some time for those chiming in late not reading prior posts on the gear, updates - fwiw.

Some fairly well knowns:
+warmish well known QS tube preamp, recently new, but burned in.
+warmish well known QS mono block tube amps, recently new
+warmish matched Brent Jesse vintage 1960s input/driver tubes
+neutral to warmish well known interconnect cables, med quality OFC
+neutral to warmish well known speaker cables, med quality OFC
+neutral to warmish well known MHDT Orchid tube DAC, neutral GE5670 Triple Mica (t/b replaced)

Some variables, and uncertainties:
-AC Power, non dedicated power circuit used, check as tbd.
-Room, very low ceilings, no room treatments yet, hard walls/floors
-Speakers with bright "ish" midrange and tweeters don’t gel well
-Speakers over 90db sensitivity are more in question so far...
-8ohm vs. 4ohm speakers may be a better match for the tube amps
-up to ~150-200hrs on preamp, amps, tubes, caps, in total, so far [est.]
-most demo speakers excluding Fritz demos are relatively new
-tube in DAC, pending replacement with warmer Telsa 6CC42 soon

If you believe some or all of these notes and assumptions listed here, what comes to mind to you first, ..1,2,3? :)

With ceilings that low, you are getting massive reflections. I would be very aggressive in knocking that effect down. Go with tweeters that have very little vertical dispersion (RAAL or AMT) and put 3 inches of rockwool overhead and in front of the speaker location. You might want to get some little mirrors and a laser pointer to figure out the angles to make sure you’re not sitting right in the worst spot.

As far as speaker suggestions... try looking at Ascend Acoustics Sierra-2 line. RAAL tweeters and ruler flat response curve.
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Thanks for the summary, decooney.
Ceiling has a thick blanket across entire area of reflection points, same with front wall. No side wall reflecting problems. Floor is carpeted, by the way. To quote my OP, “No terrible reflection points; room not overly live or dampened.”