Soundstage and image height, does it exist?

There is no soundstage image height or image at all. It's just your brain trying to make sense of what it's perceiving its a trick an illusion. Just like when you watch all those non-moving fixed images on your TV your brain makes it seem like real motion is going on.

Stereo is an illusion imaging is a trick it’s not there your brain just thinks it is. Just like your brain thinks a moving picture exists when it’s all just still images flashed at a high rate just like you perceive motion in an animated film. If you move off center the image vanishes because it’s not there. If I had only 1 ear would I hear this movement of sound? if you played only 1 speaker would it still be there? No, it wouldn’t because it was never there in the 1st place. During playback, the listener’s brain uses those subtle differences in timing and sound level to triangulate the positions of the recorded objects.