I seem to be seeing this issue after the recent 10.15.2 update.
With Diablo audio set on stereo and lowest number of channels, audio begins cutting out and totally goes silent as the complexity of the action on screen increases.
UPDATE
Okay, not sure this is an issue.
Just repaired game and when I restarted issue did not reappear. Will report back after running through some rifts.
UPDATE 2
This is still an issue although not quite as bad.
Still getting times when audio begins to cut out in very complex fights!