Any initial call to Apple will result in the usual PRAM, VRAM, SMC reset along with macOS reinstall and then a clean wipe and start again.I’ve got the issue with crackling as well. I also experienced a glitch with a YouTube video the other day. I was watching it (sound was normal etc), and then went to the previous page in Safari (the YouTube home page). The sound from the video I had left continued playing but it was skipping like a broken record. Only stopped when I watched a new video.
A prior phone call to Apple resulted in a PRAM reset which seemed to help at the time. At the moment the whole thing isn’t too severe though, and everything else has been ok.
A few of us have humoured Apple and gone through this process to prove none of this will fix the issue. My new machine has been delivered. I didn't even want it, I was happy to wait for a replacement, but Apple insisted it doesn't affect all machines and that the fix was a long way off so I should take it.