[aeroevan]

I doubt whatever plex would do could beat opus (unless it's already transcoding to opus)

[pimeys]

If you decide to stream with a lower bitrate in Plexamp, it transcodes to Opus.

You should not encode the files, just use Plex or Jellyfin and choose a lower bitrate when playing with your phone. Jellyfin uses AAC and Plexamp uses Opus.