Surround sound for onboard soundcards hopeless?

[morot]

I have lurked around various forums, and read the sticky on the subject, but I have not managed to squeeze true surround sound out of this game. I can get sound out of all speakers, but there is no actual positional/surround sound as far as I can tell (i.e. if I face away from a sound source, the sound does NOT come mostly from my back speakers).

Has anyone using onboard audio actually gotten true surround sound to work in this game?

My setup is running on a generic onboard realtek HD soundcard, with audio being output over S/PDIF to my Onkyo receiver. I have been able to achieve surround sound in other games/movies/etc.

Any help would be appreciated, thanks.