A vertical set of drivers in a time and phase correct speaker has to be aligned for a specific listening height. Vandersteen floor-standing speakers have a six-inch high alignment window that is centered on the ear height of an average person seated on a fairly low couch. To accommodate higher seating positions, the speakers can be tilted back to raise the alignment window as needed.

When the speakers are set-up for seated listening, standing-up obviously takes your ears out of the alignment window. The sonic change you hear is the difference between a speaker that is time and phase correct and one that is not. Only if time and phase were irrelevant, would there be no difference.