Just installed ubuntu 18.04 on my main desktop. I can't seem to get any sound from the front jack, which I use for headphones. The line out in the back works, but the behavior is a bit weird.
In the sound settings, if I select the 'headphones' option, which I assume would adjust the volume for the front jack, the volume of the line out in the back is changed to correspond to the level set for this option. If i raise it to a high level, the volume of the line out is thus increased, but in my headphones a short burst of crackling sound is produced. If I instead select the line out option, the sound level of the line out jack is then changed to this level instead, but no crackling is produced no matter the volume.
The soundcard is a Realtek ALC 891, and there is no hardware malfunction as it works perfectly fine in Windows.
What could be the problem?