I have an Asus Maximus V Gene, with Realtek HD audio, running Windows 8.1.
There is no dedicated Line-Out port on the mobo - there is only a green "front speaker" jack and a front "headphone" jack.
I have the audio set to "2 channel", but the volume controls still work - with the computer volume at 30% and my speakers (amped) at 9 o'clock, it's very loud.
This makes me pretty confident that it is not automatically switching to Line Out
I have gone through the settings and can't find any option to switch to line-out only. Am I missing something?