I am on an imac Pro 2017, running Big Sur 11.6.2. I had this problem as well -audio crackling, skipping, dropping out across all apps -Netflix, Quicktime, Premiere Pro, Youtube, etc. I quit coreaudio hundreds of times. I quit all other processes, restarted. Activity monitor would show 3% of CPU usage and the audio problems were still happening. I've lived with this problem for YEARS. Today, I was incredibly frustrated, trying to QC a video for a festival but unable to get clean audio. Finally, I realized that I don't need the three RAID arrays that I have had constantly running, turned off two of them. Voila, problem solved! For what it's worth, I believe it was my StarTech RAID that was causing the problem. I also have 2 OWC raids. Clearly this isn't a solution if you need to keep those raids plugged in. But it's definitely worth a try if you are being driven insane and nothing else is working. Hope this helps.