A free, open-source SoundSource alternative — per-app volume, multi-device output, and a 10-band EQ, all from the menu bar.

FineTune gives every running app its own volume slider, mute button, and boost — up to 4x gain for that one video that's always too quiet — right from a menu bar popover. Route audio to multiple output devices at once, apply a 10-band EQ with 20 built-in presets, and fine-tune your mic input, all without leaving the menu bar.
SoundSource has owned per-app audio control on macOS for years, and it's a great app — but it's paid. FineTune covers the same core workflow — independent app volumes, output routing, EQ — completely free and open source, with a few extras of its own like ISO 226:2023 loudness compensation and AutoEQ headphone correction pulled from a database of thousands of headphone profiles.
Completely free and open source (GPL-3.0).