macOS gives you one volume knob for your whole Mac. mactooloud gives every app its own. Pull Chrome to 20% without touching Spotify. Auto-Duck fades music the moment Zoom or Slack grabs the mic, then restores it when you hang up. Mystery Sound Finder catches whatever is making that noise, even in another Space. Focus blocks mute everything but your one lo-fi app. Native menu-bar app - no audio driver, no kernel extension, no virtual device. macOS 14.4+, Universal, 7-day free trial.