Two surprising things I found that improved my imaging and staging...

@sns 

I have a hard time understanding why anything between the speakers would affect the soundstage:  the sound doesn't come from between the speakers, but rather from the speakers on each side, which, in stereo make it sound like the sound is coming from between the speakers.  Please explain your rationale. 
Thanks. 

@captbeaver

When I go to that Cardas site, it only tells me distance from side and rear walls, but nothing about toe it, etc.  Did you just experiment with toe in?
Thanks. 

Speaker placement charts should all be taken with a grain of salt, including Cardas. None of them can take in account what kind of acoustic treatment you got in your room or the type of furniture and any other artifacts you may have including anything you hang on your walls. Meaning you may have a starting speaker placement with a chart reflecting the size of your room, but in the end you will have to move the speakers around little by little trusting your ears and the toe-in will end up being the most critical decision you make. Be patient, learn about YOUR system and take the time to ENJOY the journey. Being an audiophile is all about testing your system for your ears and not about finding a magic formula on paper.

Sound waves reflect and diffuse off front wall as well as side walls, floor, ceiling and back wall. The phantom center image is an artifact of these interactions. Sound waves reflecting off relatively flat and hard surfaces such as equipment front fascias results in unnatural effects. Proper diffusion is created by varied depth surfaces that neither reflect or absorb excessively.

I can only say try lowering the  equipment rack and try some proper diffusion treatments on front wall, you should hear greater center image dimensionality.  The detrimental effects of a high equipment rack will lessen if rack is further back from plane of speakers, really need to clear out space between speaker plane to at least a few feet back.

Speaker placement charts should all be taken with a grain of salt, including Cardas. None of them can take in account what kind of acoustic treatment you got in your room or the type of furniture and any other artifacts you may have including anything you hang on your walls. Meaning you may have a starting speaker placement with a chart reflecting the size of your room, but in the end you will have to move the speakers around little by little trusting your ears and the toe-in will end up being the most critical decision you make. Be patient, learn about YOUR system and take the time to ENJOY the journey. Being an audiophile is all about testing your system for your ears and not about finding a magic formula on paper.

 What a marvellous post...

Wise and well written....

My deepest respect to you.....