My audio was cracking when connecting an external audio device to my newly bought Librem 14 (with qubesOS installed).
I asked in the qubes forum and there I was recommended to contact the purism support.
The support recommended me to upgrade the EC firmware (puri [dot] sm /projects/librem-ec) and to upgrade my PureBoot (puri [dot] sm/projects/coreboot). The process was extremely easy and well documented. Thanks for that. This did not remove the crackling completely, but it made it much more silent.
Meanwhile, in the qubes forum, @saswatpadhi explained that disabling the PulseAudio “module-suspend-on-idle” fixed that issue. This removed my audio crackling completely.
I guess that updating the EC-firmware/PureBoot the support suggested to me was not necessary, not confirmed though.
I am not able to post more than two links yet, sorry for that…
This post is intended to aid those having the same issue.
Thanks to all who helped!
Daniel