Volume2 - Volume2 is an advanced Windows audio mixer, a complete replacement for the standard Volume Control.
Voicemeeter - Audio Processing and Audio Programming by V.Burel
Sound Control - App-specific volume control
JACK Audio Connection Kit - JACK Audio Connection Kit|Home
Power mixer - Power Mixer is a complete Windows volume control replacement.
Loopback by RogueAmoeba - Get all the power of a high-end studio mixing board, right inside your Mac!