Routing and Volumes
Use the Mac Mixer popover to move apps between output devices and control each route's level without changing the rest of the system mix.
Routing an app
- Click the Mac Mixer menu-bar icon.
- Find the app under its current output device.
- Drag the app row onto another device section.
- Mac Mixer writes the new route to the config file and pushes it to the HAL driver.
- The app's audio starts flowing to the selected physical output.
The first enabled output is the default route for new or unassigned apps. If a device is hidden or disconnected, Mac Mixer reassigns affected apps to the default enabled output.
Volume model
Mac Mixer applies volume in two layers:
| Control | Applies to | Use it for |
|---|---|---|
| App volume | One routed app | Lower music under calls, balance browser audio, mute a noisy app |
| Device master volume | All apps routed to one output | Keep one speaker/headphone output quieter than another |
The driver receives route configuration through the custom CoreAudio property mmcf, so volume changes do not require a coreaudiod restart.
Device controls
Each output device can be:
- Renamed in Mac Mixer while preserving the original system device name.
- Set as the only active output when you want a simple single-device mix.
- Hidden when it should not receive app routes.
- Re-enabled from the inactive devices list.
The current driver exposes 8 loopback input buses, so the active physical-output route count is capped at 8.
App identity notes
Mac Mixer routes by bundle identifier. Some apps use helper processes for audio, so the row you move may represent a helper bundle rather than the visible app bundle. Chrome-style audio helper processes are normalized where the driver can identify them.
Troubleshooting
- If a device does not appear, confirm macOS can see it in Sound settings or Audio MIDI Setup.
- If routing does not change immediately, quit and relaunch Mac Mixer so it can resync the forwarder pipelines.
- If all audio is silent after quitting, choose a physical output in macOS Sound settings. The app is designed to restore the original output on quit when possible.