After 8 years of faithful service, it looks as though my audio mixer is dying. I thought the crackling and channel droppouts were caused by a computer audio card problem, but after some comprehensive detective work (duh – it happens even when the computer isn’t switched on) I discovered that the mixer itself was the culprit.
Because the problem is on the playback channels only, this is both good and bad: 1) it doesn’t affect the recorded sound, and 2) I can’t re-patch and avoid experiencing the problem.
I’m currently researching features and costs of a replacement mixer. This one is a possibility.