Realtek HD Audio Issue

This problem involves the following hardware:

- Asrock Z77 Extreme4 motherboard (on-board Realtek audio)

- Logitech Z550 5.1 surround speakers


I'm having an issue with my Z77 audio output where my rear speakers aren't working properly. When I connect the speakers using an optical cable, everything works perfectly, but when I connect using the orange/black/green cable I'm getting some strange results. I would like to be able to use my optical cable for my TV and its inputs and still have my computer connected through the orange/black/green input.

While I am setting up the audio (screenshots below), the rear speakers work perfectly fine. However once I've saved the settings and play a 5.1 test audio clip the rear audio is outputted from my front speakers. Has anybody else encountered this and know of a way to fix it? All of my drivers are up to date.

Control Panel Sound Options