Comment 6 for bug 151634

Rayterril, could you give some more detail? If you're using Hardy and have the same motherboard as me, this is kind of weird.

On this motherboard, to enable the audio loopback, I go to gnome-volume-control, select edit/preferences and mark all the avaliable devices (just to be sure to not miss anything). With all those devices enabled (sometimes I need to close and reopen the gnome-volume-control for they appear).

Once this is done, I go to the "Options" tab. There should be there 3 "Input source" selectors. The first one is what matters (I'm not able to make the others work), and I select "Line" on there.

After this, I go to the "recording" tab and make sure the volume are adjusted (not muted). I recommend setting a low volume because, for loopback, the audio is too much amplified.

Finally, on the "Switches" tab, I enable the "Analog Loopback" checkbox and then I can listen the line-in audio on the system speakers, so loopback is working, as opposed to this bug I reported - that's why I've closed it (I read somewhere that the person which reported the bug is enough to close it, but feel free to reopen if you have reasons to think it should be).

I'm not sure, looking at your comments, if line-in don't work at all for you or if it don't work only for audio loopback; if it don't work at all, maybe you should check your hardware or open a new bug report.