Your sound options are the same as mine... the only thing i noticed is the entry EXT0 which i dont have, you could backup the registry keys right clicking on PSOBB in the tree view, select export and save it somewhere, delete EXT0 right clicking on it and delete. Then try again.
I don't know what that entry is for, but I don't have it (never had it) and should work just fine without it, either way you will have a backup that you can just double click and add to the registry so it will be as before.
Edit: I added EXT0 to my reg keys and set the same value as you and everything worked fine... so it probably wont change anything. Still worth to try.