I just bought a Roku Ultra LT to connect to my 2021 LG OLED C1 TV and Onkyo TX-SR93 AV receiver. Using all HDMI 2.0 cables and ARC between the TV and AV. The Roku is directly connected to the AV receiver. I find that the Roku is decoding Dolby Atmos and DTS audio correctly which my Roku streaming stick had stopped doing for some reason. I have two problems. When I set the Roku display type to 4K HDR Dolby vision, I get a proper TV display and everything is fine. At power off and subsequent restart, the Roku reverts back to 1080p Dolby Vision. Unrelated(?), I also get a hum from my subwoofer a couple of minutes after shutting everything down, which requires me to turn the sub off rather than leave it in standby mode. It seems to be getting a signal from the Roku which is still connected to power, even though its light is off and it doesn't seem to be streaming. Any thoughts?