Create an Aggregate Device to combine multiple audio interfaces

With an Aggregate Device, you can use audio inputs and outputs from different devices at the same time with Logic Pro, GarageBand, MainStage, and most other Core Audio-compliant applications.

When you create an Aggregate Device, you combine the inputs and outputs from multiple devices so they appear as a single device in an app. You can use an Aggregate Device to increase the number audio inputs and outputs available at the same time. You can also use an Aggregate Device if your app doesn't support using separate devices for input and output.

With some apps not made by Apple, you can use separate devices for input and output only when combined together in an Aggregate device.

With Apple apps like Logic Pro, GarageBand, and MainStage, you can use separate devices for input and output. But you still might want to use an Aggregate Device to increase the number of audio inputs or outputs.

Set up an Aggregate Device

When you create an Aggregate Device, make sure to connect all external audio interfaces first. 

  1. From the Finder, choose Go > Utilities. Open the Audio MIDI Setup application.
  2. Click the Add (+) button on the bottom-left corner in the Audio Devices window and chose Create Aggregate Device.
  3. A new Aggregate Device appears in the list on the left side of the window. To rename the device, double-click it.
  4. With the new Aggregate Device selected, select the Use checkbox for each device you want to include in the Aggregate Device. The order in which you check the boxes determines the order of the inputs and outputs in applications like Logic Pro and MainStage. For example, the first box you checked will be inputs one and two, and the second box checked will be three and four.
    The list on the right shows the currently connected audio devices and how many input and output channels each one has.
  5. To choose which device is the clock source for the Aggregate Device, choose the device from the Clock Source menu. Choose the device with the most reliable clock.
  6. Make sure Drift Correction is selected for each device that isn't the clock source.
  7. If you're using separate word clock connections for devices in the Aggregate Device, here's what to do:
    • Connect them together using word clock cables, then deselect Drift Correction for each device. Refer to your audio device product documentation for specific details on making word clock connections.
    • For devices not designated as the clock source that don't use separate word clock connections, select the Drift Correction checkbox.

Use an Aggregate Device with Apple music creation software

  1. Open your application.
  2. Do the following depending on the application you're using:
    • For Logic Pro, choose Logic Pro > Preferences > Audio, then select Devices.
    • For GarageBand, choose GarageBand > Preferences > Audio.
    • For MainStage, choose MainStage > Preferences > Audio.
  3. Choose the Aggregate Device from the Output Device pop-up menu. Logic Pro and GarageBand automatically set the Input Device to the match the selected output device, which you can change if you want to use a different input device. In MainStage, you must manually select the input device.
  4. In Logic Pro and MainStage, click Apply Changes. 
    GarageBand automatically switches to the new input device.

Use the Aggregate Device as the sound output of your Mac

When you set the Aggregate Device as the sound output for your Mac, sounds from other apps on your Mac play through the Aggregate Device. The Aggregate Device also becomes the System Setting option in the Output and Input Device menus of your Apple music creation apps.

  1. From the Finder, choose Go > Utilities. Open Audio MIDI Setup.
  2. Control-click the Aggregate Device in the left column, then choose “Use this device for sound output” or “Use this device for sound input.”

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