Unfortunately it looks like Windows 8 compatibility is going to be a minor issue right now.
As it stands the current binary distribution of v1.0 does not work on Windows 8; WInamp will not load the plugin, which indicates there's something wrong with the plugin's execution. All of the necessary pre-reqs are installed, and I've separately confirmed that VC80 and OpenAL programs are working correctly (along with Winamp itself of course), so it doesn't look like the issue is as simple as a missing pre-req. I've confirmed this problem on both on real hardware (Intel Core i7-3960X system with an X-Fi Titanium) and in virtual hardware (VMWare).
On the other hand, recompiling the plugin using the latest OpenAL and Winamp SDKs on Visual Studio 2010 produces a perfectly workable plugin.
Seeing as how debugging DLLs isn't my specialty and I don't have easy access to VS2005, I'm not going to try to guess at what exactly is going on. But as it stands the current binary will not do.
It's up to SST1 what to do of course, but the easiest solution at this point would be to just formally port the project to VS2010, rebuild it, and distribute the new binary as a new version (replacing the VC80 redistributable with VC100).
PS I'm also attaching a copy of the VS2010 compiled DLL as quick proof that it's working