AU Lab

AU Lab is a free macOS application that serves as a host for Audio Unit plugins, enabling users to mix digital audio tracks. It provides basic mixing functions such as auditioning audio, detecting peaks and clipping, and conducting double‑blind listening tests. The tool can also load Apple’s mastering plugins, including the AURoundTripAAC effect used in the Apple Digital Masters workflow.

The software targets musicians, sound engineers, and anyone needing a lightweight environment for audio mixing and mastering on macOS. It is useful for users who do not have access to larger DAWs like Logic, offering a straightforward way to apply effects and evaluate audio quality.

AU Lab is distributed as a stable, macOS‑only package and integrates with Apple’s mastering toolset, allowing users to create and decode high‑resolution AAC encodes directly within the mixing interface.