A:Answer Yes, 5.1.2 would be the max setup this can process, can also add a 2nd subwoofer as well. Shouldn't be any limitations with the xbox one x according to the specs and future firmware update. Chances are that other reviewer didn't have the proper hdmi cable or had some settings set wrong. All you're doing is passing through all the video features so even if the firmware update doesn't come in time for the series x release just connect the Xbox direct to your tv's hdmi 2.1 port then eARC to this reciever and you'll still be able to enjoy all the features like vrr allm etc. Assuming your tv has active 2.1 ports