I've recently tried to play The Suffering (one of the last Surreal Software's games) and noticed that audio doesn't exactly sound right, even with ALchemy (no EAX effects).
So I've learned that by default, ALchemy relies on Creative specific OpenAL implementation. that gives users of Creative sound cards hardware accelerated audio. Users of onboard audio have 2 solutions, patching ALchemy so that it falls back to its in-built so called Creative Software 3D Library, which is the solution I proposed initially, and realized now it's rather crappy, or install Creative's Host OpenAL implementation and trick ALchemy to use that, which works and sounds better than this Software 3D Library thingy. Host OpenAL processes all sound in software, so it works with any sound card.
Remember that weird volume problem I mentioned at that time? Well, sound volume is definitely improved with HOAL, plus there is no sound artifacts in the first cutscene. Might be just better 3D positioning. And The Suffering definitely sounds as it should with it. It seems that HOAL is crucial to have along with ALchemy if you have integrated audio. Here's the thread
on VOGONS discussing EAX stuff.
I've packaged everything needed along with instructions in a single ZIP (link in OP), so you don't have to search for and extract random stuff from Creative's installers. It's 2 min work if all goes smoothly.
PS: about that volume problem, the fist time it really was just a matter of different volume levels, and that improvement was likely a placebo effect, but with HOAL, it's really better. I think I overreacted when I said it was much better at that time, especially compared to now. Who knows, might be my brain playing tricks on me, but I'm 200% positive about sound artifacts in the fist cutscene, which are gone since I installed HOAL.