Who positions their speakers straight ahead (zero tow in) and why.

I have 1.7is w/  about 20-25 degree toe-in, tweeters inside in a fairly large room and the soundstage is pretty wide for me.  I sit 9ft away and the sweet spot is  about 5ft across.  In my room, the soundstage varies from just the sweet spot to deep behind the speakers and a few feet wide of them ( speakers are 10ft apart), depending on the music.  I’ve experimented with less toe-in to straight on; both sound good but I  prefer the tighter sweetspot (no one else in the household  can stay still and just listen  enough  for me to widen it)…BUT, I will try the incremental method again to see far wide I go and still keep the amazing detail. 

I did for years until I learned about toe in.  I have one pair of towers with no toe in and they sound good in a large open room.  I toe in the other speakers I have in smaller rooms with more surface reductions.  Adjusting speaker placement as needed and preferred is a fun part of this hobby in my experience.  

I have a pair of Snell Type A's. They are designed to go flat against the wall and face straight out. They rate in the top category for sound.

Try this, Toe in the speaker one click,1/8 of an inch at a time on both speakers at a time, stop and listen, and you will notice the center will get better without losing soundstage. It should be very noticeable. You will get a sharp center, without losing soundstage on the side. The speaker will disappear from your room.

The formal answer is that toe in affects tweeter rolloff, the width of the sweet spot, the treble to midrange balance and early reflections.  There's also the issue of some excellent tweeters may have resonances which completely vanish a little off axis.

Many speaker brands are designed to optimally perform with little or no toe-in.  I include:

• Magico
• Focal
• Revel

Magico and Revel in particular have great imaging across a wide listening area when placed with little toe-in and plenty of space to the sides and rear.

A little history may be helpful.  In the last 30 years or so tweeter manufacturing has come a long long way.  Cheap (< $50) tweeters often flat past 20 kHz, wide dispersion and low energy storage.  In the old days this was the realm of exotics, and if you wanted to hear everything you needed to point the speaker right at your head.

A related issue IMHO is the tweeter height.  Some speakers, like B&W, really should be listened to on mid-range height, not tweeter height.  So in general the best listening position for many speakers in the 21st century is with little toe in and perhaps significantly below the tweeter's laser like axis.