HD Native Thunderbolt, "Use this device for sound input"

[likewater]

Hi,
I'm trying configure my Mac to use my HD Omni's input as a System sound input. However, when I run "Audio MIDI Setup" and right-click on "HD Native Thunderbolt", the option to "Use this device for sound input" is greyed out. Please see the attached screenshot.

Does anyone know why "Use this device for sound input" is greyed out for "HD Native Thunderbolt" and how to enable this option?

I'd like to record video and audio simultaneously, and being able to configure the System microphone to be an HD Omni input, would simplify things for me. Presumably, I could then launch iMovie to record video from the built-in camera and then record audio from the System input (which I would like to be my HD Omni input #1).

I'm running Mac OSX 10.9.5.

Thanks!

[Eric Seaberg]

Are you wanting to do this to recording with your interface and software OTHER THAN ProTools? Within ProTools, the interface is selected in the SETUP menu.

[likewater]

Thanks for the reply. Yes, I want to use my HD Omni interface with the iMovie application, so that I can record both the video and audio together.