The Live:Air, Live:Air Solo and Live:Air Action apps can support audio input over the Lightning connector using professional level USB devices with Apple Core Audio support (i.e. no extra drivers required).
If the USB device works in the Garage Band app on the iPad without any extra drivers, it should work with the Live:Air apps.
Teradek has performed testing in-house with the Behringer Uphoria UMC204HD.
Customers have reported the following devices as working in their setup:
- Samson : Go Mic , Go Mic Mobile , Meteor Mic 
- Tascam : iXR
 used with the Apple Lightning to USB 3 Camera Adapter
 used directly with the USB to Lightning connector on the Go Mic Mobile -- no Apple Lightning to USB 3 Camera Adapter is required
You will need
- Lightning to USB 3 Camera Adapter
- For USB powered interfaces
- For Single USB Plugs
- USB C to Lightning Cable (for USB Powered Devices)
- USB C power adapter (29 Watts or More)
- For multiple usb devices (ie with an Apple Ethernet Adapter)
- USB Hub with at least 3 Amps of power (enough to power your device)
- Core Audio ready audio interface
Attach the Lightning to USB 3 Camera Adapter to the iPad, attach the power adapter to the Camera Adapter and then plug in the Audio interface.
Attach the Lightning to USB 3 Camera Adapter to the iPad and attach the USB Hub to the Camera adapter. Plug in Apple Ethernet and the Audio interface into the USB Hub. Ethernet should show up under Settings.
Once you have everything plugged in, open up Live:Air and add the iPad camera. Click the Audio Tab and make sure Mixer mode is selected. At this point, you should see "iPad Camera + <your device name> on the fader. Below the fader, click the button that says "On if Live" so that it says "Always on." You'll now be able to use the audio without using the camera.
- Do your due diligence for audio quality by monitoring the feed on your audio interface. The headphone port will be disabled when the lighting audio is engaged.
- Live:Air supports the first two channels as a "Stereo input" at this time, channel selection is not supported.