What is the best audiophile speaker for a tiny square room?

Hello chungjh, I'm respectfully skeptical by your assertion that your speakers require >200wpc. In contrast, I have a pair of Acoustat 1+1s, 83 dB sensitivity, which I can play to delightfully loud levels with an ARC VS110 (115wpc) with subwoofer. I happily grant you that the M545's are a very different animal but you've got less than 800cu/ft to fill (9x11x8') (accounting for 8' ceilings) vs my 12x18x8' room. Disregarding the difficulty of the load, are the M545s at 86 dB sensitivity truly that inefficient? Goodness in a 9x11' space, how loud do you play them? LOL

However it also appears that you've found them a new home already:
 https://www.usaudiomart.com/details/649563999-mint-sound-lab-m545-bass-focus-speaker-panels/

Which is a pity as I was going to suggest that you audition something in a tube amplifier before you did that. Granted tubes will generate heat but I think you might've been surprised at the sound of your ESLs without having to have a huge amount of wattage to push them.

Happy listening!

The one that sounds best to you.  Use your ears.

I would suggest the Magnepan LRS...they are ready made for a small room.  I have the MGIIIc larger ones in a  small to medium room...they work great.  The LRS also do not have huge power requirements.

Musicfan

Ignore that ad. M545s are still my speakers. Ok,  I am glad you and Russ69 think that I can get by with smaller tube amps. I don't want to use a subwoofer as my room with the audio rack is pretty clustered already. What amps do people suggest?

Tannoy Autograph mini...I have three systems...large room, medium room, small room...these are the speakers I have in my room which is 12 by 12...mesmerizing.