Get them set up well, then make them less conspicuous. I have very open weave sheer silk "slip covers" for my Brystons, in black, and also in color patterns that blend in the room. Either way enhances the "disappearing" and therefore improve the imaging. Psycho-acoustics!
Speakers "Disappearing"
I have read a lot about speakers "disappearing" so that one can't tell from where the sound is emanating. But, what about all the stereo tunes where the recordiing engineer intentionally pans the music to come from one side or the other? Can the speakers be made to "disappear" in that situation? Or, is it just the nature of the particular recording?