Some facts about true 3D positional audio:
0. It's a forgotten 90's technology.
1. Possible on regular stereo headphones.
2. Allows the player to determine the direction of the sound source with very high accuracy (not only 'somewhere back' like in surround sound).
2. Gives also elevation cues (above, below) with similar accuracy to point no 2.
3. Uses information on exact sound sources location in the game acquired from the game engine.
4. Any sound implementation that does not is only a gimmick, including Creative CMSS-3D and similar.
Note:
You can test true 3D audio right now by watching some HRTF demos or by enabling it in any existing game that uses OpenAL.
http://www.reddit.com/r/oculus/comments/1fzonq/
More information:
http://steamcommunity.com/discussions/forum/10/864980278184895534/