How to Adjust Volume for a Multi-Output Audio Device on macOS

To manage volume on a Mac using a Multi-Output Device, adjust each included speaker or headphone output separately in Audio MIDI Setup. Select the individual output in the sidebar and change its active Volume sliders. The Mac’s volume keys and the Output volume slider in System Settings may be unavailable while the combined Multi-Output Device is selected. If an output has no software volume control, use its physical controls or the software supplied by its manufacturer.

Why the Mac volume slider is unavailable

A Multi-Output Device sends the same audio to several outputs at once. macOS can route the stream to those devices, but the combined device does not always expose one shared software volume control. That is why the keyboard volume keys can show a disabled symbol and the system slider can appear dimmed. This behavior does not necessarily mean that audio has stopped.

Apple’s Audio MIDI Setup guide calls the routing choice Primary Device. It describes audio sent to that primary device as also playing through the other devices in the stack. The Primary Device menu is not a master-volume slider, so changing it is not a reliable way to set the loudness of every output.

Adjust the volume of each output

1. Confirm the active output. Open Apple menu > System Settings > Sound, then click Output. Select your Multi-Output Device so the Mac continues sending audio to the combined outputs.
2. Open Audio MIDI Setup. Use Spotlight to find the app. If its Audio Devices window is hidden, choose Window > Show Audio Devices.
3. Select one physical output in the sidebar. Click a device that is part of the Multi-Output Device, such as the Mac’s built-in speakers, USB headphones, or an audio interface. Select the individual device, not the combined Multi-Output Device.
4. Move its active Volume sliders. If software volume control is available, Audio MIDI Setup shows blue sliders. Adjust each channel to set that output’s level. Apple notes that these options depend on the device; for a stereo output, keep left and right at the intended balance.
5. Repeat for the other outputs. Select each included output in turn and set its level. Play audio at a comfortable level while you make small adjustments, then check that every destination is audible and balanced.

For a device-specific setup, see Apple’s description of the Audio Devices window. It explains that the options on the right change with the selected device and that blue Volume sliders indicate available software control.

If a volume control is missing or inactive

Not every output lets macOS change its volume in software. If selecting an individual device in Audio MIDI Setup does not show active sliders, look for a volume knob, buttons, remote, or a manufacturer control app for that speaker, headphones, display, or interface. A slider that is absent or gray is a device limitation; there is no universal setting that makes every output’s software volume adjustable.

You can also adjust the level inside a media app if it provides its own volume control. That changes the source level going to the outputs together; it will not balance one speaker against another. To balance outputs independently, use the individual device controls described above.

If you select a single output in System Settings > Sound > Output, macOS shows the controls available for that device. For example, Apple’s sound output guide describes the Output volume slider and notes that additional options in Audio MIDI Setup depend on the Mac and connected device. A single-output selection can be useful when you want to use the Mac’s normal volume keys, but it stops sending sound through the other destinations in the Multi-Output Device.

Quick troubleshooting checklist

• In Audio MIDI Setup, confirm the intended devices are checked under Use for the Multi-Output Device.
• For volume changes, select each underlying output in the sidebar; do not expect the combined device itself to provide a shared slider.
• If a device’s sliders are inactive, use that device’s own controls or manufacturer software.
• If the Mac’s volume keys must control one output, switch to that single output in System Settings > Sound > Output. Switch back to the Multi-Output Device when you want audio on all selected devices again.

In short, set the relative level at each output that supports software volume, and use the device’s own controls where it does not. The Multi-Output Device handles routing; it does not guarantee a universal master-volume control.