PUM: Silence the Embarrassing Pops

One day, you’re giving a presentation to an important audience, and you know that you need to lower the volume on your Mac. What you don’t know is that the technical staff in charge of setting up your presentation rig have left all external speakers on their maximum volume. You press the volume lowering key on your keyboard, and an enormously loud popping sound blows every speaker, and renders your entire audience deaf (either momentarily or permanently). How do you avoid this travesty in the future? Let’s find out!