Some days ago I´ve installed Windows 8 and all my motherboard drivers. Since then I was having trouble getting audio from my headphones (which are connected to the front panel of my desktop computer) and through my speakers which are standing beside my monitors and have a volume control wheel.
The idea is to have both of them always plugged, whenever I want to use the speakers I turn the volume up on the speakers and if I need to use headphones I just get my headphones on and lower the volume from the speakers.
Since the update I was able to listen to audio from one or the other but not both. And today I found the correct configuration.
I have an Asus Audio driver software which stands on the system tray. I clicked on the app and selected “Connector Settings” when I selected AC97 Front Panel instead of HD Audio Front Panel, I was able to get the audio from both outputs.
Hope this helps for you too!