I only have digital output available. Can someone please point me to a 15.3 diagnostic procedure?
Yes, review the following guide…
https://en.opensuse.org/SDB:Audio_troubleshooting
In particular, run the alsa-info.sh diagnostic script as explained here…
https://en.opensuse.org/SDB:Audio_troubleshooting#Script_to_run_to_obtain_detailed_information
…and share the URL to the uploaded output so that others can advise further.