I'm using MBP M1 Pro 14" 16GB RAM. I'm having an Cayin RU6 external DAC connecting to my MBP and I'm also experiencing sound crackling. The issue happens more frequently when the system is in high memory & CPU usage BUT the issue is gone if I use the internal DAC under the same circumstance. So there is something wrong with the way the system communicates with the external DAC. I also tried installing Parallel Desktop and play music in Windows 11 but the sound crackling still existed with the external DAC, but not with the internal DAC. So I think it's not an issue with MacOS software as the issue occurs on both OS.

It seems that the issue is caused by RAM usage as describing here https://old.reddit.com/r/macbookpro/comments/vluqp9/psa_suffering_from_your_m1_macbook_pro_making/ I tested it myself and my usb audio dropping occurred exactly when the memory pressure turned to yellow.