Thanks for the reply above. It comes close to addressing my own issue. I've successfully installed the OBS NDI plug-in. I'm able to get the video feed from my iPhone no problem. Also getting the audio signal from the iPhone mic. However, I'd like to use a USB mic instead that I can plug into my iPhone. The mic is called an Apogee One. It has two channels. Channel 1 for an external mic and channel 2 for an instrument (guitar). I'm able to see the NDI meter in OBS respond to the channel 1 signal, but for the life of me I cannot see nor hear the channel 2 signal. I checked the Apogee One against Garageband and both signals come through fine. I've fiddled with Stereo, Mono, checking and unchecking all 6 tracks in the Advanced Audio Properties of the NDI Source and no luck. Any insights would be greatly appreciated. Thanks.