Any fixes for persistent NO SOUND issue on 16" MBP (2020) OS 11.2…?

Speakers are not recognized by my computer. Numerous calls with Apple Support ("AS" herein) team members… Tried all manner of solutions. After 3 months, 7 store Genius Bar visits, the computer was replaced. Worked great for 9 days, then…pffft! No Sound. - Another 90 min phone session with AS yesterday… Erased HD - Re-installed Big Sur… Still no joy. - Tried several of the suggested solutions in the "Restarting Sound Service?" thread ( https://apple.stackexchange.com/questions/16842/restarting-sound-service/121342#121342 ) No go. Last note: I'm a musician. Default DAW: Logic Pro All software duly purchased or licensed... 3rd party software: Native instruments Komplete 8 (use only some of it), Sibelius I suspect possible culprit(s) Native Instruments… ?? Any ideas where to look?