Hi, if you open up the plugin (located where you mapped the Tdarr documents folder) in a text editor you can see what conversion settings it’s using or you can see it here:
https://github.com/HaveAGitGat/Tdarr_Plugins/blob/master/Community/Tdarr_Plugin_s7x8_winsome_h265.js
So the video transcoding in this plugin is done by HandBrake and uses the following:
-Z "H.265 MKV 2160p60" --all-audio --all-subtitles
Unlike FFmpeg, HandBrake is a bit more limited in what it can do with audio. Here you can see that the default for this preset is stereo audio:
https://handbrake.fr/docs/en/latest/technical/official-presets.html
You can pass through audio using for example the following switch:
-E copy:ac3,aac,eac3,truehd,dts,dtshd,mp3