cant go much beyond 10" wide to fit in the apce between the amp Boxes and the corners.
Please Please don't tell me you are placing such awesome speakers in a corner or near a sideboard or drawer with sharp angles - this will definitely affect the soundstage and may collapse it to the speakers (edge diffraction = claustrophobic sound)
=> this might be a major part of your problem...any reflections within less than 7 msecs can severely affect the openess of the sound...the worst is that everything collapses to the speakers. My rule of thumb is a minimum of three feet from side walls but four feet or more is safest. Remember our ears sense timing for where a sound comes from....the time a signal arrives is how you interpret where it is (you have to go 10 DB SPL louder to make your brain pay attention to "loudness" rather than arrival time cues) Now when you clutter or crowd early arrivals with edge diffraction of reflections it can really mess up the size of the soundstage.