Audiobook - Compressor & EQ

[TheDreadPirate]

If no transcoding of the audio is happening then ffmpeg and any compression options aren't applied anyway.

And even when audio is being transcoded, the server is not coded to apply the selected down mix algorithm to stereo/mono sources.

Jellyfin apps can have compression and EQ options in them but the official apps don't and plugins cannot add that level of functionality to them. The only app I know of with EQ is Symfonium. But it doesn't support book libraries. And none, AFAIK, have in compression functionality.