When you added the roxul centered behind the speakers, it centered the phantom image better for you I understand, an overall improvement in image specificity. Did it have any effect on the depth of the soundstage? Ie did it make the soundstage extend back less in your opinion?
OK, that was interesting. The panel only had an easy-to-notice effect on instruments with prominent highs, so I tested with the first track from "Metheny Mehldau", guitar and piano. Guessing the percussive nature of the instruments helped as well.
Removing the panel made everything seem more intense & detailed, but also seemed to shift the soundstage a couple of feet further away from me, as if the instruments were level with the window pane rather than with the speakers. I didn't like the effect, so I put the panel back and after some side-to-side experimentation ended up with it in the same spot as before. Oddly enough when I centered the panel between the speakers it seemed to make the room too "dead". I was walking around shaking my head at how much of a difference one panel could make.
On a positive note, I'm finally happy enough with the room (if not with the colour of the speaker stands) that I'm going to stop tinkering for a while and listen to music instead
