Topic on Talk:Prince of Persia: Warrior Within
I did 😉. And I also tried out the other solutions to restore EAX, with the same result.
To be clear: The surround-sound works! It's just all the effects like reverb that don't work. As far as I can tell, this is a common issue.
WW is also the only title in the trilogy that supports EAX Universal. Maybe that's the source of the problem.
PS: It might also be the case that this is a specific issue of the GOG version that I am using. But I couldn't find any information to verify this.