I thought you didn't want "close proximity" to eliminate boominess. My concern is being too close to a wall on the left.
Adrian is concerned about having no wall behind the left. I guess neither of us have a beautiful HT room that so many picture here.
Bob, in my "experience" (don't laugh!
) boominess is too broad a concept to so quickly equate with corner loading. I think boominess is a potential outcome of corner loading, but it is all about the complex reflections of a room. The corner will emphasize lower notes, but in a given room that may flatten the bass curve at the listening position, not spike a range and cause booming. I’m not disagreeing with you, just saying the issue of placement is not subject to such a clear rule - I wish it was, so I could stop moving my speakers around.