Hi
I am just curious about the terminology
Soundstage according to Gordon Holt about "The accuracy with which a reproducing system conveys audible information about the size, shape, and acoustical characteristics of the original recording space and the placement of the performers within it."
So you are transported via your speakers and rig to the "you're there space" listening to the acoustics of the original space where the music was recorded.
For a speaker to do this, the room and placement for the stereo maya magic have to be just right. Specifically you don't want the spatial cues your expensive DAC painstakingly decoded being keema'ed and butchered by the spatial cues coming from your room. ***IF*** you have your reflections treated, then psychoacoustics ensures that the illusion of the soundstage is created. typically it is behind the plane of the speakers (OB, planar and boxes will all be "different" and we have our preferences)
In making your reflection free zone, I was listening to a Glen Kuras talk on yt where he talks about the importance also of treating the reflection while preserving the timbral quality of the direct sound (and I have no clue on how to do that. BBA sucks the shimmer, leaves the longer waves unaffected and cannot meet that requirement)
What are you talking about when your talking of "the sound stage becoming restrained" with and without the foam plugs ? It is the inverse problem of what I have and off a different wall.
ciao
gr
see these pages
https://www.psaudio.com/pauls-posts/dialing/7784/ and
https://www.psaudio.com/pauls-posts/depth/