Sound is better when I stand up?

Your tweeters should be within 1-2 inches of your ears ,depending too what type f speakers, drivers, wave guides, compression drivers many variables.

the first thing you should mention is the speaker brand , and tweeter,driver type 

you have very low ceilings meaning very reflective unless you have ample room treatment .

Hi all!

Cool. Let's recap:

@audioman58 I did mention the brand - Reference 3A MM Gen 2. Stock tweeters; I have ceiling corner foam triangle baffles but am now considering some ceiling  hanging foam frames

@mbmi swivel chairs. Huh. Good point. 

@grauerbar You're right. I mean, how much listening do I do on my feet? I have no mantelpiece upon which to lean with my tumbler. 

@holmz Great picture of my wife's reaction whenever she sees a new piece of audio gear I hadn't told her about. 

@bigwave1 Yes, I can adjust my stands by adjusting the spike depth. Thank you for the suggestion. 

@avanti1960 I had the 3As toed in slightly and now have gone back to the recommended no toe in. That did make a positive difference in the sound. 

To those who mentioned the triangular distance, I have gone with something closer to 1-1.2 ratio, like @tomcarr ​​​​@clearthinker suggested. That helped, too. 

Can't give up the wingback, though. It's so comfortable. 

@simao    

I note you have removed the toe-in.  This is the purist position.  If the production was classic then there was a spaced pair of dipole microphones in front of the musicians.  If you don't toe-in you are hearing what the mics heard.  If you toe-in, the image of the sound will be spread outwards. A 'hole' may appear in the centre.

Speaker toe-in and listening distance are of course related.  Less toe-in is has a similar effect to listening from further away.

I do think you're making a mistake with the wingback.  If you like to rest your head perhaps a chair with a smaller headrest to the back of your head not impeding soundwaves' access to the ears.

Or listen with headphones?

Many reviewers like EXTREME TOE IN where the left speaker is aimed at your right shoulder and visa versa........It's an interesting sound...you should try it .

simao    

I note you have removed the toe-in.  This is the purist position.  If the production was classic then there was a spaced pair of dipole microphones in front of the musicians.  If you don't toe-in you are hearing what the mics heard.  If you toe-in, the image of the sound will be spread outwards. A 'hole' may appear in the centre.

Speaker toe-in and listening distance are of course related.  Less toe-in is has a similar effect to listening from further away…

I think that another school of thought is as the room get brighter in reflections, one may also chooser to toe them in.
Particularly if the speakers have a narrower radiation pattern.
If they are super wide, then the toe doesn’t matter at all.
But sometimes if they are bright, then toeing them out can reduce the direct SPL.

There is nothing seemingly pure or impure about it.
I thought it is like a tone control to tailor the speakers bespoke to the room the speakers are in.