A deeper more holographic soundstage.

More than anything it’s the room.

A balance between diffusion surface and volume, reflection and absorbtion is decisive... No room is similar even with the same form and the same number of doors and windows at the same place...

Why?

Because the acoustical properties of the furnitures and walls and ceilings and of the floor can be different between these 2 similar rooms...

Then even with same geometry and topology. the acoustical content that constitute the building room and furnitures will act dramatically...

In my room the soundstage and imaging and even timbre perception was increased greatly by the right balance between reflection, absorption and diffusion...

Just one tip to make you smile but it work: sound waves hate empty corner...

I replace 4 of my 5 ceiling corners with polyedral flowing shape...i use five cents materials... Results: increase in the perception particularlyof high frequencies and more refine sound all across the scale...My room was already heavily controls tough....it is just an example of what can work in a specific room...

In acoustic small change can made great improvement...

"Reading all the comments really demonstrates there's a long way to go in audio before we all agree. It almost seems totally subjective and opinion driven sometimes."

@jimofmaine.....*G*  Heart of the matter, frankly.  Mho, the only thing that can be said to be in total agreement is that things plug into each other.

Until Bluteeth and other wireless occurred....blew That away.....*shrug*

I have no proof of this but life experience:

But I also think there are certain ways your brain 'likes to...or prefers to' listen to sound. Probably different for everyone. I went deaf in my left ear for a few months in 2020 and now that I have recovered what I lost, I appreciate what your brain does to compensate. You need around 40-50% hearing in one ear to begin to 'place' and locate things in space.

For some reason, I don't hear a better soundstage when I close my eyes...even in the dark.  I do 'feel' like I hear a better sonic picture when the room is dimly lit and my eyes are open and looking somewhere between the speakers (in a blurry gaze) but obviously thinking about the music.

I'm sure a lot of you have certain conditions that you prefer when doing critical listening.

Roxy,

Wow that was all a bunch of conjecture which each participant believes is helpful. Some possibly useful but most doubtful.

Heed the expert from Atlanta who wrote the book on improving sound. ($500/day per session) He tells everyone the 1st thing to do is move everything out from between the speakers. This is 100% correct.
If you can't move it then lower it.

In my setup every piece I play has the vocalist 4 feet behind the speakers. Perhaps I do not listen to crappy recordings but who does?

The rules of physics still apply. If there is not distance open to the wall behind your speakers you will fail.

On symmetry: Also a no. Reducing early reflections is everything.
The more symmetry, the more reinforcement of early reflections.

News soon to be common knowledge:
The Amp makes all the difference.

Sometime in March 2021, A well established, US based maker will be releasing a new &  affordable product which beats all other comers. No it's not Pass. 

Sorry for the teaser. 

I have not made that little since the early 90s.

Heed the expert from Atlanta who wrote the book on improving sound. ($500/day per session

My mechanic charges way more than that.

On symmetry: Also a no. Reducing early reflections is everything.
The more symmetry, the more reinforcement of early reflections.

While early reflections are very important the rest of this statement is nonsense unless you are breaking symmetry to fix a worse issue.

The rules of physics still apply. If there is not distance open to the wall behind your speakers you will fail.

The rules of physics still apply. This statement however shows a one dimensional knowledge of acoustics (physics). It's the different between knowing what you are doing and parroting rules of thumb from others.