This just started happening to me today out of the blue. I didn’t install anything new or anything. It’s not Ctrl + S - if I press that at the menu, it says sound is disabled, and when I press it again, sound is enabled. But there’s no sound. And like HiHo said, Diablo III is fine, and so is YouTube in the browser.
SC Remastered has the same issue. I cranked the volume sliders to max in both games. Nothing.
If I put on my AirPods, the sound comes out of those. But not the Mac speakers or the headphone jack.