Applies to: All macOS Sierra compatible interfaces.
With macOS Sierra, you are able to use Siri from your Mac. You can use any microphone connected to the first input your Focusrite interface with Siri, however Siri has its own audio settings separate from the rest of macOS.
In order to access Siri's audio settings, please click on the Apple icon in the top left corner of the screen and select System Preferences. Then select Siri, pictured below.
Once you have the Siri settings open, you should see an option for Mic Input. Please ensure that you have your interface selected here and the your microphone is connected to Input Channel 1 on the interface.
You should now be able to use any microphone connected to the first input channel on your interface to give Siri voice commands.