PC: Surround sound problem using an AV receiver?

Hi,

I'm playing the pc version of the game and i wonder a bit about the audio settings. maybe you can solve this. my pc is connected to an 5.1 AV receiver via a GTX580. the receiver is set to "Multichannel" and in-game audio is set to "home theater"...but it appears like the rear speakers are improperly used by the game. they are very quiet and you cannot locate where the sound comes from. for example i would expect voices from the rear if the camera points away and my played character stands with the back to the speaking person. you know what i mean ? 😉 but sound effects like birds flying around appear to be played through the rear speakers. i do not experience the known "no voices" issue.

in other games this works perfect...so is it because there is a wrong setting or does the game uses the rear speakers not that way?

if i set the AV receiver to "all channel stereo" all speakers are used. if AV is set to multichannel and the game to TV or headphones, the rear speakers are also used...so issue or not? 😉

the windows setting is set to 5.1 surround.

thanks for help