The above screenshot from Emby for Android TV shows two audio options that only appear when I connect my device to a TV, HDMI audio extractor or AV receiver with DTS decoding, and we should turn them on or off depending on their decoding capabilities.   The same should apply to multichannel PCM/AAC, the option to transcode them to Dolby Digital should only appear when I connect my device to a TV, HDMI audio extractor or AV receiver with Dolby Digital decoding, to still be able to enjoy 5.1 audio