I am just curious, I use raw and everything including DTS:x gets bitstreamed to my AVR which is exactly what I want. How does auto differ?
Yes, that's absolutely fine - as long as the AVR supports all formats, RAW can be used and the results are exactly the same. Auto does the same thing but will convert codecs to stereo PCM if the EDID indicates that the AVR doesn't support them - these days, not an issue we often come across. So Auto honours the EDID and RAW sends the raw bitstream regardless of the EDID.
Just to point out that because I always prefer a belt and braces approach, I used to advocate using RAW. ...until I realised, that bizarrely, some soundbars don't support DTS, so I changed that to Auto otherwise DTS would end up a hissy mess with such devices.
Thanks for your solution. One more question if you can answer. Kodi and VLC has no USB storage access on Z9X Pro. Is there a way to get it working?