Soundstage

Thanks Duke. If I’m understanding correctly you are describing the kind of sound that I really like (with the early sidewall relections). Found in bipoles (e.g. my ancient Mirage M3s), wide dispersion bookshelf speakers (my LSA bookshelf) and I would guess omnidirectionals. The speakers disappear, and you can walk around the room and the speakers remain disappeared.  Not a goal, just a description of a kind of sound I like.

Interesting post Duke. Because some of the most enthusiastic comments on my system have to do with superb image focus and a stage that extends beyond the speakers. My feeling for some time now has been more you are there than they are here. My room, in other words, disappears. The untreated (well, HFT) side walls do not seem to interfere with rock solid imaging. Each record is not only a different sound, it is a different world. Some you are right in it, others it is further away, some it is rather flat, still others it extends deep and wide.

This is actually one of the hardest things to get across to people, because there is a tendency to assume what you are hearing is the system. The more that is the case the easier it is to evaluate. But the more the system disappears the harder this becomes. Depending on what I play you could leave convinced my system is flat and narrow, or deep and wide, but only a great deal of time listening to a wide range of music will reveal the truth, that it was the recordings not the system.  

I suspect this is because as important as the speakers and the room are, still they are but two on a very long list of things that matter.

I have had different models of Audio Physic speakers. They all produced a wide soundstage beyond the speaker boundaries. I have tried many positions in a few very different rooms. The speakers just disappeared in a very wide stage. Most were older models though, when the original designer Joaquin Gerhard was still with the company. (Designer spelling may be incorrect.)

Very cool speakers,
after years of trying the equilateral triangle at 8 feet 
and trying to extend the 8 feet feet listener to my rooms max of 8 ft 6 in
I tried something different .
My speakers manual suggested 8 feet apart and 8 to 10 feet from the listener , so what's the difference ?  
The angle from the listener to the speakers ,
from 60 degrees to 47.2 so if you haven't already maybe try
moving your speakers to 8 ft 10 in  apart with your 11 feet to the listener
you'll have an angle of 47.2 degrees .
Just a thought and maybe worth a try .
https://www.calculator.net/triangle-calculator.html?vc=&vx=132&vy=132&va=&vz=106&...

Don't know where this equilateral triangle deal came from but it is erroneous.  

Speaker setup is a two-step process. 

Step one, move them around relative to the walls listening for bass balance and tone. Listener position matters as much as speaker location so listen to each speaker location from closer and further away. Step One the speakers do not need to be perfectly equidistant or symmetrical, but pretty close. 

Step Two, now from the smoothest sounding location measure very accurately to get them perfectly equidistant and symmetrical. Listen for image focus and sound stage width and depth. Adjust the toe in very slightly and the image focus and depth will be greater. Adjust the toe out very slightly and the sound stage width will expand. Equidistance and symmetry must be precise each and every time or you will lose image focus and think it was due to changing toe when really it was sloppy symmetry. 

When you are happy with the balance you are done. Does not matter what the distances are. That is all simplified to the point of rubbish. This is how you do it.