To get a head start re Audyssey App look at Gene’s interview: (
https://www.audioholics.com/editorials/denon-marantz-audyssey-multeq-editor-app) and my review of the Marantz SR7012 (
https://www.audioholics.com/av-receiver-reviews/marantz-sr7012-receiver-review). When the Denon AVR-X8500H review gets published there’s a section in there as well on the Audyssey app.
In a nutshell you want to use the app going forward and limit your maximum frequency to the ~Schroeder frequency of your room or a suggested max of 5kHz (this is what Anthem does with ARC). The app just takes longer as it communicates each sweep. Doing sweeps on the Denon X8500H with 15.2 channels (but only 13 active at a time) took over 45 minutes!!