Create several new audio tracks in your GarageBand project.

Ciick the Input Device pop-up menu, then choose the Aggregate Device.

If you want to use multiple headphones, you'll need a splitter or a headphone amplifier to send Garageband audio to those headphones. GarageBand can only output audio to a single device.

Click the Output Device pop-up menu, then choose the device your headphones are connected to.

To set the inputs and outputs for your recording, choose GarageBand > Settings (or Preferences) > Audio/MIDI, then do the following:.

You can record multiple tracks at once with an Aggregate device in GarageBand, such as a podcast with multiple USB mics:

For each device that is not the clock source, select Drift Correction.

To set the clock source for the Aggregate Device, choose the device from the Clock Source menu. Choose the device with the most reliable clock.

Drag a device to the left for lower input or output numbers, or drag to the right for higher numbers.

To reorder devices after you've selected them, drag a device under Subdevices left or right.

Learn more about how to identify Aggregate Device inputs and outputs

With the new Aggregate Device selected in the sidebar, select the Use checkbox for each device you want to include as a subdevice 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.

A new Aggregate Device appears in the list on the left side of the window.

Click the Add (+) button at the bottom of the sidebar of the Audio Devices window, then chose Create Aggregate Device.

From the Finder, choose Go > Utilities, then open the Audio MIDI Setup application.

When you create an Aggregate Device, make sure all external audio interfaces are connected to your Mac.

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