This happened a while ago and I can't tell anymore why or when... It just didn't bother me enough at the time but now I can focus on this issue.
Whenever I have a cable plugged into the headphones output of my soundcard and there is no sound playing (like youtube, mp3) it starts to buzz (60Hz buzzing). If I remove the power chord from my laptop, the buzzing stops. I am an electrical engineer and I think that the soundcard somehow turns off the power when not in use and that's why I hear a current loop. Would make sense in a laptop anyway to save power.
I workaround this problem by having a VLC player play any random file at 0% volume. That keeps the soundcard going and not buzzing. But I would like to go back to a state where I don't have to play silent music in the background to have a non-buzzing soundcard.
I use Ubuntu Studio 18.04.
uname -r 5.3.0-24-lowlatency
cat /proc/asound/cards 0 [HDMI ]: HDA-Intel - HDA Intel HDMI HDA Intel HDMI at 0xc4310000 irq 51 1 [PCH ]: HDA-Intel - HDA Intel PCH HDA Intel PCH at 0xc4314000 irq 52
(Topic is about PCH Soundcard) Thanks for any help!