Strange fuzzy sound?

I think the first thing I would do is try to isolate the problem. Does this occur on all files and file types or specific files? Does this occur only when using Audivrana or does it also occur if using iTunes for playback? What kind of DAC do you use? How is it connected to your MacBook? How much RAM do you have? What version OS are you using?

Do you have another USB cable to try? If it is a genetic cable I have experienced more than one problem with those over the years. Also try another USB port on the MacBook.