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

I just put in Thiel CS 3.7 in a slightly larger room than yours. I removed a closet door to give me a bit more space, especially the space from my head to the wall behind me. I am assuming your space is a dedicated listening space. 

https://systems.audiogon.com/systems/7605

1) If you can do anything with this room them get some GIK Acoustic treatments (or from anybody else). GIK will work with you  remotely to find the best products to use for your room. My stuff was the lowest priced ones and the 9 panels totaled $700. They make an incredible difference. That floor stander in my room sounds great after the panels were added. I am shocked that my floor stander works so well in this room.

2) I am going to explore adding Digital Room Correction next after I get my speaker repaired (figure that out tonight). With DRC I would not even need the panels but they are supposed to make the DRC easier to implement in the treated room. I use ROON for my streaming digital and the DRC will be implemented as Convolution file(s). Not too expensive to get a professional sound engineer to implement this remotely. PM me if you want more details. I am in the process of doing this, though I hit a road block with a speaker driver problem that will get solved soon.

3) If you  have separates why not go for a Class AB amp such the CODA #8, Bryston 4B3, Parasound JC5, Hegel 390 integrated. These are not that expensive and run cool. I will be running 2 Benchmark AHB2 which I am  not sure would work with your speakers. PM me  if you want to talk about the AHB2, I did a lot of research on this amp into low impedances.

4) The KEF LS50 META maybe something you would like. It is a perfect fit for your room size. I replaced my KEF LS50's with the Thiel CS3.7 but the LS50's worked great in my treated room. Prior to treatment not so great.

Big speakers in a small room. Been there, done that, got it to work great.

@chungjh Great that you got panels coming your way. It will open up a world of possibilities for your speaker selection.

I chose the Thiel CS3.7 because I always wanted it. It was my second favorite all-time speaker and a local sale came up, so I went and picked it up. I would be reluctant to buy a used unit that needed shipping. The original packaging is now old.

The Thiel CS3.7 has a bit less bass than the speaker i was expecting to the get for this small room, the Yamaha NS5000. Both speakers sound best in a larger space but the sound I have now is very good. I think once I get the DRC implemented I will have excellent sound. I may have to spend another $1000 to fix my driver issues (with OEM drivers) but this speaker will be my, "to the grave office speaker", so I want it perfect.

Some other floor standing speakers that I demoed and now know they would fit my room were:

Vivid Kaya 45
Paradigm Persona 3F
Magico A3
TAD ME-1 (not floor stander)
Yamaha NS5000

BTW - I started measuring my room with a Minidsp mic and the REW software running on my Windows laptop. A lot of great info can be gained especially for folks like us in small rooms. This was how I discovered a problem with my driver though I cannot hear it.

@zaphod2006 I had the Audience 1+1 and the KEF LS50 driven by a Peachtree Nova 150 in the the same room for a few months. The 1+1 was 2x the cost and I wanted to like it more than the LS50 however, I could not get it to sound good. The imaging was bad the soundstage was not correct. I just could not get it to sound correct in the small room. I even called Audience to ask advice.

It think the 1+1 needed more space from the front wall and I did not have the space to do so. The KEF LS50 was perfect in my acoustically treated room. I think the Coincident design makes placement easier.

My new Thiel CS3.7 also has a coincident driver design (Thiel COAX driver) which I think helps in placement.

@chungjh Yesterday I was testing out how loud I could take my speakers since I am replacing the tweeter and midrange (COAX) next week on my Thiel CS3.7. So if I blew them no big deal.

Normally I sit with my back to the speakers with my head looking into 4 feet of closet space (my computer monitors). Since I was doing a special listening session yesterday, I thought I would try to optimize the sitting position. So I turned around and faced the speakers.

There was a dramatic change in my perception of the sound just because I was looking at the speakers. The speakers did not disappear as before. I changed the volume to various levels and still the same issue. I think the small room is the cause of this. Likely a bit of claustrophobia at work.

I just put my KEF LS50s back into the room (the old Thiel drivers are now removed) and the same thing. Looking at the speakers takes some of the magic away. When I first setup this room, I thought it was a bummer that I could not face the speakers but it turned out to be a stroke of luck.

BTW - I do not know if it is the lack of bass on the LS50 but the difference in sound quality between the LS50 and the CS3.7 (in my small room) is massively favoring the CS3.7. The LS50s is sounding as perfect as it can but the floorstander makes such a dramatic improvement. I think any of the floorstanders I listed before would have had similar results.

@chungjh Did you come to a resolution to your speaker and room issues?

My floor standers in the same size room as yours are sounding amazing with the recently implemented DRC.  So good in fact that I bought a second amp yesterday to run as mono block, a Benchmark AHB2. I can make my speakers sound even bigger and more dynamic with more power (I tested this out). I have a second DRC implementation (another Convolution file) that I will use to deal with the additional bass from the additional power. All of this is done digitally on ROON (or JRiver) before the bits hit my DAC.

A lot of misinformation on this forum on DRC and I am glad I did more research and tried it out. A lot of info on this on AudiophileStyle and AudioScienceReview (ASR). I do not have any DRC involved on my Tuner or SACD player but I play those are mainly used on headphones.

A few years ago the founder of ASR, Amir, posted to me on a thread that I have to use DRC in any room. I thought he was a little over the top on that. Today, I am thinking he knew what he was talking about.