Does anyone know how to get more soundstage height?
This is going to sound simple minded, but the best staging height I ever got was when I had a room with 14 foot ceilings. Now, you can't exactly go raising your ceiling unless you buy the place above yours and demo it, but maybe you can get the effects with dampening and diffusion. Just like everyone recommended a rug for your floor to ease reflections, give a look into an acoustic treatment for the ceiling - even the standard "popcorn" ceilings have made a difference for me (though they can look a little tacky in a clean, modern design such as your home).