I've always set up my missions to use EAX but I rarely used effects that had a lot of reverb. I use a X-Fi Titanium Fatality sound card and it supports EAX without needing Alchemy, although I did use Alchemy years ago on an Audigy card. I don't like the 3D effects or the crystalizer so I leave them off. One thing I don't really like is that I have to switch the card to game mode for games and entertainment mode for tv and movies in the Creative control panel. EAX in thief sounds great and gives me environmental surround so I can hear voices, footsteps and ambients all around me.

Oddly when I play Thief 2 with the card set to entertainment mode, I can hear everything as if I was inside a massive single room brush. The door attenuation has no effect.