Does anyone know if this also impacts head tracking devices such as TrackIR or Freetrack?

As of today, I can reproduce this issue with 100% reliability. Meaning I can't play multiplayer anymore. :(

I have a pair of G930 headphones as well and have the exact same issue. It occurs only in ArmA 3, as far as I have noticed.
To be more specific, it seems that the "ambient" sounds such as wind and insect singing seem to be "skipped". I can play the game as it is, but the issue does get very annoying after a while, which prevents me from having longer sessions.

Additional info: running Win8.1 64 bit and no dedicated sound card, just the USB headset with virtual 7.1 sound.

I wholeheartedly upvoted this. Implementing this could completely change the dynamic of firefigts in ArmA (for the better).