Q: About compatibility

Okay, lets start now.
Developing a game and it`s main porpuse is to be real as can be. Definitely it points to surround systems and 3D Audio. But the game should be playable without surround system.
So question: What should i look and which librarys(and how) use to make a very compatible sound system for a 3d game.

Cheers,

Mirko