why 3D Holographic sound

Two likely issues. One is the vertical dispersion of the tweeter is different for your standing and sitting positions. You might try changing the tilt of the speakers if possible.

The other is the reflected sounds probably differ between standing and sitting. Look for differences in the first reflection surfaces (left, right, up, down and even behind) between standing and sitting. Strong reflections will muddy the image. Changing speaker position or adding sound absorbing materials at critical points may help.

You'll probably have to experiment to find a solution, but it will probably be centered around a factor noted above.

depends on what you're sitting on. a high-back chair with a cushion by your ear will of course sound very different than a shorter chair with nothing immediate by your ear absorbed or reflected

I have speakers tilted up about 2" and about 7 feet apart, and 3feet from back wall, my room is about 12x17' and carpet floors,using VR3s' speakers,kown to cast a preatty decent sound stage,just replace my VTL 5.5 for a joulet 150mk11, though was my preamp, was wrong,need to find a solution,when standing the sound and imaging is absolutly Gorgeous, will try difusing panels, next:

"I have speakers tilted up about 2""
There's your problem.

HI, thanks, Etran, will try leveling speakers, will get back to you with the results, thanks: and by the way,upgraded from VTL, to joulet 150mk11, ans boy what a diference; much more resolving, and organic sound, upgraded due to imaging problem, was a win,win, situation in my case: