What seems to be missing ? The Zensor has a 7 inch woofer, most bookshelf speakers has 6.5 and smaller, I think your next upgrade would be a FS or a really good bookshelf speaker which might cost you more than 50K, unless you go the second hand route. Look into Dynaudio, B&W.
I saw an SVS floorstander in the Buy and sell section, I think it fits your budget, going with an FS will greatly improve your midbass performance
Revel F35 at 68K looks promising