Speaker toe-in & stereo imaging

Just a few thoughts to add to those above:
A speakers crossover point (and woofer dispersion/size) will also effect toe in especially since some 2 way units will drive their woofers above 4K. The beaming that results will cause a greater variation in the upper mids between on axis & off axis response.
The distance from the speaker pair & the proximity of the side walls can also be very significant. Trying a variety of positions is the key. Changing the location, height or angle of a speaker usually changes the sound far more than many often spoken of tweeks or cable changes.
-Torin

It is such an easy thing to test yourself with your own speakers in your own room, it is speaker and room specific.

In my experience most box type speakers with tweeter etc sound best overall with toe in about half way between straight ahead and directly pointing at listener. If speakers are very close together less toe in required. Want best compromise of wide sound stage but solid deep center.