If you are currently using an older version or are new to the software, here is how to set it up: SoundSource Release Notes - Rogue Amoeba
Apply built-in effects like a 10-band Equalizer or Headphone EQ (with thousands of calibrated profiles) to any audio source on your Mac. SoundSource 5.3.8
This version family provides comprehensive control over your Mac's audio that goes far beyond the built-in system settings: If you are currently using an older version
Adjust the volume of individual apps relative to each other and redirect audio from specific apps to different output devices (e.g., play music through speakers while routing a Zoom call to a headset). SoundSource 5.3.8