Well openAL then or something similiar - some kinda hardware mutli-channel audio solution...
There are already libraries available for at least one, probably more, such audio solution. Unfortunately, due to superstition or something else which is beyond my comprehension, they're used by very few people. Speaking of which..
I prefer something like ageia integrated into b3d natively rather than using a dll/wrapper/decls as there seems to be some issues with more extensive use resulting in random MaVs.
Given that the entire Blitz3D function set is found in a DLL - albeit that it's eventually statically linked - I think you can safely assume that there are no issues with extensively calling a DLL. Anything which MAV's with extensive use is either a bug in your code or a bug in theirs.