You can combine several audio devices into a single device, called an aggregate device.
Aggregating devices lets you increase the number of discrete audio inputs and outputs, for example, your SUBPAC and an audio interface/headphone amp
1) In the Audio MIDI Setup app on your Mac, click the Add button at the bottom of the sidebar in the Audio Devices window, then choose to Create Aggregate Device.
2) Rename the aggregate device, click it in the sidebar, then enter a new name. (i.e. SUBPAC/AMP)
3) In the right side of the window, do the following:
- Select the devices to use: For each device you want to include in the aggregate device, select the Use checkbox.
- Check that each device is set to the same sample rate, to ensure the aggregate device works correctly. You can also enable drift correction for each device.
- If the devices in your aggregate device aren’t synchronized using hardware, you need to enable drift correction, also known as resampling, to compensate for drift in the data between devices.