Hi.
My sound settings page is similar to yours except in the Windows sound device box. Mine has one selection "configure" which opens the Realtek audio device which is enabled as the default device and functions properly.
When flying the "sound off" does not appear on the screen.
What I don't understand is why, when opened, a wav file contained in the main FSX sound folder will produce the appropriate sound and be heard but no sound of any kind is heard when running the sim program. Very mysterious.
Any thoughts would be most helpful.
Cheer. Don