I am inclined to think that off-center images being localized at the speakers may well be a loudspeaker issue rather than a room one. Maybe a driver breakup mode, or a diffraction artifact, or a crossover phase anomaly, or a box resonance (either internal or panel). In my experience, sidewall reflection issues skew the image to one side or the other (and often will pull the sibilants to one side of a center vocalsit's voice), but I don't think they tend to consistently localize the sound images at the drivers. You said the center vocalist images very well, which makes me think it's more likely the speakers than the room.
You might try some felt rings around your tweeters in case it's diffraction. Two bucks each from Madisound.
Best of luck to you!
Duke
You might try some felt rings around your tweeters in case it's diffraction. Two bucks each from Madisound.
Best of luck to you!
Duke