SoundSource - The sound control that should be built into MacOS
Volume2 - Volume2 is an advanced Windows audio mixer, a complete replacement for the standard Volume Control.
Boom 3D - Audio enhancer with 3D surround sound
Sound Control - App-specific volume control
Noizio - Feeling that the noise of the big city is too much for you to bear?
Volume Scroll - Volume Scroll lets you control your main volume by hovering with your mouse cursor over the top...