In version prior to vista, they were an api called Directsound which allowed to access sound devices directly.
On top of that api, exist DirectSound3D which allowed to perform spatial sound effect from stereo speakers (for example making feel a noise or a voice come from behind you)
Since Windows vista, Microsoft put efforts to enhance the sound driver model, making impossible to control the sound device from userspace directly.
In order to solve compatibility problems, Microsoft added an emulation layer for directsound.dll (the dll which implement the directsound api).
However, that layer doesn’t really enable the DirectSound3D api. Attempts to use DirectSound3D will result in every sound being played in mono speaker mode (so all spatial effects are lost).
So is a there a software or a virtual driver to restore full DirectSound3D functionalities ?
I took a look at IndirectSound, however, it’s for 32 bits Windows only and it doesn’t support eax.