I attach a string to my listening position. I then measure the inbound corners of both speakers to ensure they are the same. I then follow the same procedure for the outbound corners. This method not only provides perfect speaker distance but also exact angle (toe in).
Tweaking Your Speaker Placement
"Depending on the speakers an 1/8” move in the right way can have a significant impact."
What I am curious about is how one can verifiably move a speaker exactly 1/8th of an inch? My speakers on stands weigh about 60 pounds each and being bookshelf speakers, they are a little top heavy. They are also on IsoAcoustic Gaia's, which don't really slide too well.
How do you do it?