A neighbor visited yesterday for a while when she came over to pick up her kid from my home. I was working from home in the afternoon. I had come home early because the postal carrier had delivered an NOS rectifier tube and a matched pair of NOS driver tubes for my AVA Ultimate 70 from Jim McShane, which I installed in the amplifier and which significantly improved the amplifier's sound. When my neighbor came over, I was listening to music while sitting at my computer at a desk in the rear corner of the room (where there is a big 45hz bump).
She walked into the room and told me that the music sounded good. She sat in my listening chair, closed her eyes, and listened to Norah Jones. (I stopped working and listened, too, but she had the sweet spot.) After approximately three tracks, she turned to me and asked, "Where is the middle speaker?" I replied that the speakers are there and pointed to the two HT2-TL a few feet away from her. She replied, "But her voice is coming from there", pointing to a spot in between the speakers and in the center of a five foot wide threshold into the kitchen. I stated, "I know." Then, she stated, "But where is the middle speaker?" She actually got up and stood between the two speakers, which was about six feet away from where she had been sitting, and looked for a (non-existent) center channel speaker.
I think that I have the instrument placement, width-wise anyway, pretty well dialed in.