Ok, I got it again and noticed there is another commonality, so far at least, it's always occurred when playing a video from plex in firefox and/or falkon. Just to clarify the problem once triggered, remains for all sounds.
I played an entire movie this morning with mpv this morning and had no issues.Pastebin/sysinfo
I went through the journalctl logs and found nothing at all useful. The only thing that even could be pertinent is a series of messages originating with kde_powerdevil
Jul 03 08:38:44 kaos-desktop org_kde_powerdevil[1849]: powerdevil: Enforcing inhibition from ":1.11" "firefox" with cookie 5 and reason "video-playing"
Jul 03 08:38:44 kaos-desktop org_kde_powerdevil[1849]: powerdevil: Added change screen settings
Jul 03 08:38:44 kaos-desktop org_kde_powerdevil[1849]: powerdevil: Added interrupt session
Jul 03 08:38:44 kaos-desktop org_kde_powerdevil[1849]: powerdevil: Disabling DPMS due to inhibition
Jul 03 08:38:44 kaos-desktop org_kde_powerdevil[1849]: powerdevil: Can't contact ck
Jul 03 08:38:45 kaos-desktop org_kde_powerdevil[1849]: powerdevil: Enforcing inhibition from ":1.11" "firefox" with cookie 6 and reason "audio-playing"
Jul 03 08:38:45 kaos-desktop org_kde_powerdevil[1849]: powerdevil: Added change screen settings
Jul 03 08:38:45 kaos-desktop org_kde_powerdevil[1849]: powerdevil: Added interrupt session
Jul 03 08:38:45 kaos-desktop org_kde_powerdevil[1849]: powerdevil: Can't contact ck
Jul 03 08:38:58 kaos-desktop org_kde_powerdevil[1849]: powerdevil: Releasing inhibition with cookie 6
Jul 03 08:38:58 kaos-desktop org_kde_powerdevil[1849]: powerdevil: Can't contact ck
Jul 03 08:38:58 kaos-desktop plasmashell[1703]: qml: applet destroyed
Jul 03 08:38:58 kaos-desktop org_kde_powerdevil[1849]: powerdevil: Releasing inhibition with cookie 5
Jul 03 08:38:58 kaos-desktop org_kde_powerdevil[1849]: powerdevil: Restoring DPMS features after inhibition release
Jul 03 08:38:58 kaos-desktop org_kde_powerdevil[1849]: powerdevil: Can't contact ck