Question about speaker angle

Is this a theoretical question or a fact?

Mostly depends on speaker design, their size, how far they are apart, your listening distance and placing in room.

If you want a hot presentation (more high frequency energy) choose good toe in and if you want coherency on a wider area decrease it. 

Keep in mind that toe in alters high frequency response, the level of side walls reflection, and the relationship of direct and early reflected sounds.

Only experimentation can give you the best coherency considering also what kind of tonality your speaker has and how wide you want your sweet spot.

Different speakers = different speaker designs and components = different sonic signatures = different results  = There is no silver bullet answer.

There are three rules to follow.

(1) Hands-on Experimentation 

(2) Read the speaker manual 

(3) Repeat Rule #1.

Tannoy recommends pretty extreme toe-in. I own a pair and I have them toed in as much is possible in their current location. To me, they sound very good this way.

Generally speaking, the more you toe-in speakers, the more solid and precise the center image will seem, but, this comes at the expense of a less expansive (wide) soundstage.  You need to experiment, that is the only way to know what is right for your situation and personal taste.  the same actually goes with all aspects of speaker and listening position placement--a lot of trial and error is required.  Don't for get to also dial in speaker height and rake angle (how much the speaker is tipped backwards (i.e., the degree to which it is angled toward the ceiling).