5.1 headphones, rear and back sound doesn't work

[WooCash]

Hi, I have reinstalled my OS and I've noticed that 5.1 in my headset doesn't work properly. When in games I can only hear people on left and right. However, when someone is directly in front of me or behind me I cannot hear. I tried to play around with Realtek but nothing helps. My headset did work properly before so I don't know how to fix this.

Headset: Tritton 720+

 

[WooCash]

It doesn't have to be connected via optical so I used a splitter with 1x usb and 2x jacks (mic and sound) which seemed to work perfectly untill I reinstalled Windows. It might be something with Realtek, but I can't work it out.