I have had some issues with crackling sound and Steam on my latest build - notably during Fallout 4.
To fix this I came across this post and this video - unfortunately the links in the video are dead.
I believe it is caused by high rate sample rate audio being play though low rate kit.
For my future reference and for anyone also stumbling across this - I please see a link to my git up which has the pulse audio .conf fig file that - at least for now- works for me.
To use - backup your /etc/pulse/daemon.conf file with the below code to save a copy in your home dir:
sudo cp /etc/pulse/daemon.conf daemon.conf_working
then either clone file from git or change manually with
sudo gedit /etc/pulse/daemon.conf
*Other text editors are available!