Originally Posted by michaelk
My first guess would be to check the mixer settings. There could be an unused input that is enabled and for some reason is experiencing EMI. Try disabling inputs or change the gain control and hopefully the crackling will go away.
There could also be a common component in the output section that could be starting to fail. Not much can be done about a failing component. Replacement is usually the cheapest solution.
As I was searching for inputs, I decided to see if anything was different and I saw that the 'PulseAudio' "Volume Meter" was always TOO THE MAXX, i tried to reset the Interal Audio Analog Stereo, and 'sometimes' it plays the music/video just right, then other times (mostly) it goes right back to the crackling