Confused (z77 extreme 4 sound)

Ive recently upgraded my monitor to a LG 27UD68P 27 inch Ultra HD 4K, which has 1 headphone 3.5mm output, 1x  display port and 2x usb ports.

I got the screen to use with my pc via display port (no problems),

and the 2x usb ports for my xbox one s, and my slim ps4.

Using the ps4 and xb1s on the usb, I get no sound unless using headphones (plugged directly into the monitor) but id like the sound via my bose companion 5.

 

I bought a 3.5mm to 3.5mm cable,and thought is run this from my headphone out on the screen, to line in on my onboard 7zz extreme4 onboard sound card, (which is enabled showing in my win7 device manager).

 

Im hoping someone may be able to show me the error of my ways and tell me how (if possible) to get the screens hdmi ports sound from my bose 5 via my pc, im really confused!

If I may ask, how did you resolve your issue in the end? It would be good to know in case any one else needs the information later on down the line.