corelli:
We have discussed this several times above (but its a long thread, right?).
Have built custom wall hangings that kill reflection behind AND between my two DIs and this alone has made a tremendous improvement in a large but poor acoustic space. Doing room correction afterwards fine-tunes the result but my experience in the studio and audiophile worlds is that physical room correction always beats signal alteration.
Have found that removing the reflection behind the speakers allows them to stand in their own glory and this improvement is arresting in strength.