Speaker Placement - Frequent Placement Changes?

I measured my setup, room is 156" wide x 288" (13’-0" x 24’-0"long)

My speakers, center of front face, are

40" in front of rear wall; 27" from the side walls either side (102" between) 

single centered listener, distance center of speaker face to ears is diagonally 150" (180" from front wall) (108" open space behind to rear wall)

speakers toed-in aimed directly at center listener and tilted back so that Tweeter’s are aimed up at seated ear height, (see mid horn and woofer positions in photo above, they are a mirrored pair, tweeters inside L edge and inside R edge

Alternate Toe-In for Two Off-Centered Listeners

Chairs are each 24" off center, now diagonal to face of speaker is 145"

Aim Left Speaker to Right Listener; Aim Right Speaker to Left Listener

They cross 48" diagonally (44" horizontally) in front of the listener’s ears.

Good stuff @elliottbnewcombjr. My guesstimate of speakers crossing between 24” - 36” was off from your 48”. How much have you played around with rake/tilt? 

I had my Tannoys tilted back pretty far (almost 2 degrees) using thread extenders with my IsoAcoustics Gaia when utilizing extreme toe-in. I have since moved back with more traditional toe-in with the axis crossing 12” behind me, but didn’t change the tilt. I can’t remember if it was tcutter or someone else, but they had suggested keeping tilt and toe-in equal. Because of this, I reduced the tilt which seemed to help with the phantom center cohesiveness. 

Interesting nonetheless @elliottbnewcombjr, and greatly appreciate the pictures which aid in understanding! 

Tilt Back

1st. issue is aiming the tweeter's narrower wavelengths directly at the listener(s) seated ear height

2nd issue is altering the angle of reflection of the drivers with wider wavelengths

3rd issue is physical time alignment of the face of the drivers themselves

https://en.wikipedia.org/wiki/Loudspeaker_time_alignment

and toe-in alters the reflections off the side walls of course.

Having a dedicated sound room is a blessing, and I apologize to anyone who does not. I use a high-quality and very comfortable office chair, which the back comes up slightly higher than my shoulders, below my ears. I have a vinyl runner so I may move the chair forward or back, which for me, depends on the recording. I sit far from the rear wall and prefer near-field listening. My best, MrD.