The FFXIV client seems to be ignoring the new per app audio device settings in Windows 10 update 1803.

I have tried setting it to multiple other audio output devices and it always comes through on the system default device instead. This setting is working for all of the other software I have tried it with (discord / chrome / VLC / etc).

Article describing the new Windows setting for reference:
https://www.groovypost.com/howto/new...-april-update/