Hi, I've read similar topics but still can solve my problem. Just connected my new Roku.
- 3820X - Streaming Stick 4k
- Last firmware (10.5.1)
- Audio output via optical to a Sony amplifier
I connect the PS4/Chromecast Ultra to any of the HDMI inputs of my (6-year-old) FullHD TV and it works, 5.1 no configurations needed. I bought the Roku because now I only have a Chromecast 3 (no 5.1) and wanted a more open/compatible/updated solution than Chromecast Ultra. But this feature is a must, don't want to use the PS4 for NetFlix and Roku for everything else.
Roku audio and HDMI settings are in auto (I tried to set custom and DD but same results).