I just find a lot of made up excuses when it comes to treatments. Most people spend leagues of time worrying about the wrong things--when room/speaker makes by far makes the biggest difference in sound. Even 213Cobra has never tried an external piece of room treatment in his room, so until then all of his opinion is really just pure speculation.
agreed....
Could it be improved by room treatments? Perhaps. But these room treatments would necessarily affect the visual appeal of the room; and this is a compromise that is not acceptable - to me, at least.
Gsm18439, looking at your space, I can understand your reluctance. Stellar aesthetically.
DSP or digital domain correction is still a potential option for many and is obviously the future....