Currently, the "Auto Passthrough" option for digital audio only outputs in either Dolby Digital, Dolby Digital Plus, or DTS. This is not ideal for stereo content, because other lossy formats like MP3 or AAC get transcoded to Dolby Digital, and lossless formats like FLAC are unnecessarily compressed to lossy DD.
I often use my Roku TV to listen to my lossless music collection through Plex, and it's frustrating that I can't listen to it in the best quality without changing the passthrough setting and breaking surround sound for video.
This would be solved if the "Auto Passthrough" option defaulted to PCM if the channel was not outputting pre-encoded DD/DD+ or DTS.