Have you got the 4k 120hz update? I didn't notice the sound issue since the update but I also ended up putting it back to 60. 120 also disables the option to hard clip for HGIG.I had this same needing to go to bed problem with my 65jz1500!
One thing I did notice on the series X in 120hz mode on hdmi 1 is that the sound from earc to Sony htst5000 (hdmi 2) cuts our every few seconds. I switch to 60hz mode and it's fine.
It's ok for me as I prefer Dolby Vision gaming which is 60hz anyway. But worth noting perhaps as an issue. Going to try some different combos of settings to try get it to work well.
Otherwise it is bloody fantastic. Fired up some star wars, jjohn wick 3 and some Disney+ marvel movies and I am very impressed!
What picture mode is most accurate? Filmmaker? Also is there any settings that I must turn off or on. New to the Panasonic UI, too used to the LG one.