Speaker Placement

I'm sorry if I misunderstood you Roscoe50 but when your reference is 60 degrees off-axis (i.e, an equilateral triangle), 160-170 degrees IS sitting almost directly behind the speakers.

In regards your response to what Manitunc is saying, the nature of stereo may be two point sources, but the nature of hearing is not. What we all (supposedly) are trying to achieve is a reasonable facsimile of the original performance using those two point sources. In my experience headphones do not do that. Although I do occasionally listen to headphones, there is no way I'm giving up my speakers (arranged in a slightly isosceles triangle) for them.

When a recording engineer produces a stereo mix, he is trying to produce a stereo mix. If he wants to simulate what a live audience hears then he would make a mono mix.

To be directly on axis, 160 to 170d is ideal as it is the approx angle of your ear.
The 'nature of hearing' is indeed two point as we have 2 separate ears. Listening is stereo is an attempt to make the most of this.

I prefer headphone like stereo dynamic w/o the headphones.

Abucktwoeighty-- For all practical purposes, all of our ears are indeed designed alike. Have u read up on S-Logic technology by Ultrasone hphones? They caution not to reverse( some like to hear Beatles 2 track records in reverse channels) the earpieces.

The sound live audiences hear is subject to almost infinite variables such as their seating relative to the speakers and performance source, the subsequent sound mix, ambient (reflected) sound, direct sound from the stage, and the hat size of the person in front of them.

the hat size of the person in front of them.

Folks will get a chuckle out of this but it's true.

I'll state again that our ears are not designed alike. My ears do not protrude from my head as far as some others, like Alfred E. Neuman, and others, which makes me hear a little less. As far as "practical purposes", yeah, I guess we all use them to listen with. We just don't hear the same. When I hear yellow, you may be hearing amber.