We're talking about a difference of three inches at the sweet spot. Unless you are in the very near field this is a very small difference in the angle from the speaker to you. A corresponding very small change in the front to back tilt of the speaker would compensate for the difference. If you like the chair I would start with tilting the speakers.
Just out of curiosity, what speakers are we talking about?
Just out of curiosity, what speakers are we talking about?