Uninstalling the "Smartbyte software application" absolutely helped.
It's amazing to me that almost 4 months from this original post, this issue is still going on, and Dell is still pushing this stuff. I just got this update on or around the 13th. I was never affected before.
Now I can listen Spotify again!
Thanks for this info, it really helped. Appreciate the effort you put in - "I updated or reinstalled every single driver, BIOS, even tried latest drivers from Intel, Realtek, switched to native microsoft hd audio drivers, messing with power saving settings - but nothing helped." - because us fellow users benefited from your contribution.
Very well done!
Something to obvious at all!
A terrific thank you!
From an IT old pro!
thx for your help - Smartbyte software unistalled and sound on my Dell Inspiron 7566 is perfect again ;-). I spent 1 day with reinstalling of all around "sound"...