I never quite got the EAX to work right when I was playing WoW (yeah, I guess I've officially stopped now), but I always attributed it to being Creative Labs' fault. But now I am led to wonder, after Blizzard had to go and break Sound Blasters with a new software in-game mixer system.
From the Creative Labs Forums:
As many Creative soundcard owners are discovering, Blizzard recently made changes to the WoW client that have impacted the audio experience significantly. Our developer relations group were given minimal advance warning that these changes were about to occur, and our subsequent requests to Blizzard for clarification as to why the changes were made have gone unanswered.
The new audio implementation in WoW uses a 3rd party audio middleware system which offers a generic software mixer with some reverb effects. Creative has worked with the middleware company in question and already implemented a hardware audio path that enables 3D audio mixing and DSP based effects processing on Audigy and X-Fi cards. "Bioshock" uses this system to great effect, and it is relatively straight forward for developers to support. We have offered to help Blizzard enable this hardware audio path but they haven't taken us up on it.
Many Creative soundcard owners are pointing out that their audio experience is nowhere near as compelling as it used to be, which is a great shame. We will continue to seek a better resolution to the current situation with Blizzard. In the interim, we would encourage Creative soundcard owners to let Blizzard know that they would very much like to have their audio experience restored to its former glory.