True in some cases. It's my experience that this solution works only if the receiving device is capable of decoding the Dolby Digital signal. If the receiving device isn't, then it does not work, and setting HDMI to "PCM Stereo" does not appear to work, either.
Keep in mind that for passthrough-only models (those lacking a Dolby decoder), setting it to anything other than DD+ (auto or manual) will limit the output for NetFlix/Prime/Hulu/D+/etc to PCM 2.0: these apps exclusively use DD+ and/or rely on system configuration for audio stream selection/availability.
(For those models with Dolby decoders (e.g. 4640 or 4800, or TVs), manually setting it to DD transcodes the DD+ to DD, so it isnt a problem)
So, while this may provide a fix/workaround for UPnP/DLNA streaming in some cases, it will limit output to PCM 2.0 for all of the DD+-only apps for passthrough-only devices.
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My new Roku Ultra LT system surround sound is broken with the latest update. I had to reinstall my older Roku 3 model to get my Tablo recordings to again play. I tried all the settings for surround sound on the new model with NO JOY. The older model works perfectly. The update has simply broken the Ultra LT unit. No work around that I can determine.
Update: I reinstalled the Roku Ultra LT (Model: 4662RW OS Build 10.0.0 4198-46) to do additional testing. All my other apps Netflix, Hulu, SiriusxM and Spotify all are working normally with surround sound. I now believe the problem now lays with the Tablo app. Its' reporting that Roku is telling the app that there is no surround sound capability.