I stumbled on something. Initially for other testing purposes, I created a full SBS (3840 x 1080) 3D mkv file out of a 3D-BD iso. However, I just gave the file a go with the Z9X. It played flawlessly. So, for those who like to playback/create full resolution SBS, it may be nice to know that this is possible. Note that I only tested with x264 encoder. X265 is on my to-do list. Also, for now, the mkv is created without subtitles. Proper 3D subtitling has its caveats to this type of video. These first need tackling.