FWIW, I remember playing with this last time I saw the thread. I just tried again. I see no such variation (or less that 1 db) as I try five different positions (one sofa, small chair on either side). So the spread is about 11 feet.. I'm about 15 feet from the VP150 center. I see the other speakers vary as I change positions (e.g. left gets weaker as I move far right, but not the center). I'm using the built-in tones from Onkyo receiver and an RS spl meter.