Can I use two interfaces at the same time for more I/O? (aggregation)

Yes, Mac OS allows you to use multiple audio devices at once and use them as-if they were a single device. Through a process called Aggregation, inputs and outputs of the separate devices are combined and can be used simultaneously.  For example, you can aggregate 2 ONE’s, effectively creating a device with 4 output channels.

Apogee supports device aggregation for a maximum of 2 devices only on Mac OSX 10.7 (Lion) or greater.

Apogee devices that support Aggregation:

• Duet 2
• Quartet
• GiO
• JAM
• MiC
• ONE

To create an aggregate device and use multiple interfaces simultaneously:

• Open Audio Midi Setup (Located in Applications/Utilities/ on your Mac)
• Click the + from the button left of the window
• Select “Create Aggregate device”
• Double-click the newly created device’s name “Aggregate Device” and rename it if desired
• In the right side of the window, select the devices you wish to aggregate. For example ONE, Built-in Input, Built-in Output.
• For best results, be sure Apogee device is selected as the Master Clock
• In your recording application, select the device name you’ve just created.
• To select this device to be your default for Mac sound, Right click (or control click) the device in Audio MIDI Setup and select “Use this device for sound input/output”
• Select the Output speaker channels by clicking “Configure Speakers”, selecting the stereo tab and assigning destinations for left and right channels
• Select “Done” button and you’re all set.