Decklink 4K Extreme & BMCC with NTG-2

I'm trying to capture directly from both the BMCC and NTG-2 with the Decklink 4K Extreme using the XLR input that is built into the capture card.

Media Express doesn't seem to give me any options to select a different audio input device (unless I'm missing it somewhere) so I'm not sure how to do this.

bumping this up. Hoping a Black Magic staff member might see it.