Hi @Bjorn_Konigsson,
I’d guess, you need to place the ffmpeg binary in the RoonOnNAS/bin folder, as Synology’s own version does not provide all audio codecs.
The new version might give you a hint, which ffmpeg version is used. the path of the used version is given in the RoonOnNAS.log.txt file, which is located in the RoonOnNAS directory of your selected database shared folder.