I second the thought on placement. I have been trying different ones over the past three years and have only just found what I consider the best so far. The second-last try imaged well but had a midbass hump and no low bass; a new placement took care of both. Frustratingly, the latest greatest speaker position was an accident--happened because kids overnighted in the listening room and the speakers had to be moved. Never underestimate the value of kids.
Getting the rack out of a corner node helped too.
Getting the rack out of a corner node helped too.