I have my Roku Ultra 2020 connected to a Yamaha AVR (which decodes Atmos) and output to a new Samsung Smart TV Q80 series ARC HDMI port (high-end TV). In the Roku audio settings, I selected auto-detect as it is recommended. When watching a Netflix 4K movie, the sound on my Yamaha AVR front panel indicates DD Atmos/PCM. Does this mean it will decode any format between DD Atmos and PCM?
That is what it seems to be saying, but after fiddling way too much with mine, I found out that Auto Detect doesn’t do much with stereo or 2-channel PCM. Only the front speakers have sound, the rears don’t. Changing to Auto PassThrough results in much better performance and allows my audio system to overlay Dolby ProLogic on stereo and does a real fine job of it too.