The master volume macOS wouldn't give you.

Your Mac's volume keys do nothing on a Focusrite Scarlett or any other fixed-level audio interface or USB DAC — just the crossed-out HUD. Loudini gives those outputs a real software volume your keys can actually drive, with its own HUD. Same for external-monitor brightness.

Free & open source · macOS 14.4+ (Apple Silicon) · no drivers, no kexts