Drop outs after Big Sur upgrade

I am running a MacBook Air 13" 2020 with intel core i7 and 16gb memory. I used Audacity a couple of months ago and obtained perfect vinyl to digital transfers. However, having got back to my archiving last week I have drop outs virtually continually. There have been no changes to the system or laptop in the meantime except an upgrade to Big Sur 11.6 and upgrade to Audacity 3.1.2. I have tried increasing buffer, made sure all other apps are closed,etc. etc. but no luck. Grateful for any suggestions.