SystemEQ

SystemEQ applies a 10- or 31-band parametric equaliser to everything your Mac plays. It includes a large AutoEQ library of headphone correction presets, a hearing calibration mode, room-tuning helpers and real-time visualisations.

It routes audio through the BlackHole virtual audio driver, which adds a little latency and means apps sending sound directly to an audio interface bypass the EQ. The project targets macOS 13 or later and is a young, single-maintainer app.