How to combine multiple audio interfaces by creating an aggregate device on Mac OS X v10.5 Leopard

By creating an aggregate device, you can use more than one audio interface at the same time with audio applications like Logic, Soundtrack Pro, GarageBand, or most other Core Audio-compliant applications.

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Set up an Aggregate Device

  1. Open the AudioMIDI Setup application from /Applications/Utilities.
  2. Choose Open Aggregate Device Editor from the Audio menu.
  3. Click the "+" button under the Aggregate Devices list to create a new empty device.
  4. To rename the device, select the name and type in the highlighted area.
  5. All connected audio interfaces appear in the Structure area. From the Use column, select the audio devices you wish to include in your aggregate device. The order you check the boxes in determines the order of the inputs and outputs in applications like Logic, Soundtrack Pro, and GarageBand. For example, the first box you check will be inputs one and two, the second box you check will be three and four, and so on.
  6. Designate one of the audio devices as the clock master by selecting its radio button in the Clock column.
  7. If your audio devices all work with word clock, connect them together using a word clock cable. Connect the cable from the device you designated as as clock master in step 6 to the input of each other device. Refer to your audio device product documentation for specific details.
  8. If any of your devices do not work with word clock, enable the Resample checkbox for the devices that are not designated clock master.
  9. Click Done.

Using your aggregate device with Apple professional audio software

Read on to learn how to use an aggregate device with Logic, Soundtrack Pro, and GarageBand. Your aggregate device may also work with Core Audio-compliant applications from manufacturers other than Apple.

To use an aggregate device with Logic or GarageBand:

  1. Open Logic Pro or Logic Express.
  2. Choose Logic Pro > Preferences > Audio or Logic Express > Preferences > Audio and select the Devices tab.
  3. Select the Device drop down menu and choose the aggregate device from the list.
  4. Click Apply Changes at the bottom-right of the window.

Note: Configuration in GarageBand is similar. Choose Preferences > Audio/MIDI to select the Audio Output and Input devices.

To use an aggregate device with Soundtrack Pro:

Note: Soundtrack Pro uses the default output devices defined in Audio MIDI Setup. 

  1. Open the Audio MIDI Setup application from Applications/Utilities.
  2. Choose your aggregate device from the Default Output menu.
  3. Note: There's no need to use an aggregate device for input in Soundtrack Pro. The Recording tab allows you to select any connected input device for each track.

Important: Information about products not manufactured by Apple is provided for information purposes only and does not constitute Apple’s recommendation or endorsement. Please contact the vendor for additional information.
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