BF3 Sound Settings

Hi,

As would like to chose best settings for my sound setup:

Xonar DG and Sennheiser HD485 Headphones, and I cannot find anywhere information about:

SOUND SETTINGS in Battlefield 3:

Which options does what(which one does for example 5,1 sound ??)

TV

HI-FI

HOME CINEMA 

HEADPHONES

WAR TAPES

Also, in the config file: PROF_SAVE_header, we have this line:

GstAudio.SoundSystemSize 20

What the value means ???

Regards

kuman