System Configuration : System Setup : Configuring Avid HDX, Pro Tools|HD, and HD Native Hardware Settings : Identifying Audio Interfaces

Identifying Audio Interfaces
If you have multiple audio interfaces of the same type connected to your system, before you make audio connections to them, you should confirm the identity of each interface. This ensures that you choose the appropriate interface in the Peripherals list when you define its inputs and outputs in the Hardware Setup.
To identify audio interfaces in your system:
1 Choose Setup > Hardware.
2 From the Peripherals list, select an audio interface connected to your system.
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Use the Up and Down Arrow keys to scroll though the Peripherals list in the Hardware Setup.
3 Make sure the Main page is shown.
4 Select the Identify option, located in the lower left corner of the Hardware Setup. This illuminates all the LEDs on the front panel of the selected audio interface.
5 Make a note of which interface in your studio setup corresponds to the identified interface.
6 Repeat the above steps for each additional audio interface in your setup.