BehringerUMC 404HD

[blandis]

[Explaining a little bit further] You need to configure ALL of the inputs of the UMC404HD that you intend to use in JamKazam during the "configure audio" steps, including what instrument(s) you expect them to be carrying. This is a little different than, say, a Digital Audio Workstation (DAW), where you instruct it to "be ready to use any and all of the inputs of the UMC404!". Think of JamKazam more like, "OK, now I'm going to simultaneously record and bounce down to stereo the following instruments on the following channels". Being a multi-instrumentalist (and having Behringer's XR18 as my interface), what I do is build the biggest audio setup I would anticipate using in a JK jam, which includes 1 vocal track, a stereo keys track for my synth, a mono guitar amp DI track, and a midi track triggering Addictive Drums stereo VST. When I go into a session, each one of those tracks are built, and JK mixes them into a live stereo track. I can mute the ones I'm not using for that particular session, or unmute if I switch instruments. The tricky part is balancing those tracks, because the people on the other end of the session only get 1 stereo fader from me, combining all of the tracks, like a stereo mixdown track. So it's up to me to balance them with the JK mixer before JK sends the audio to others,
Also, very important: you will want to ensure you turn off any local monitoring of your tracks, by turning the 404's Mix knob all the way to PB (playback). This way you will hear what is being sent to others over the JK connection, and you won't be confused why others don't hear you ("(but I can hear the signal in my phones on UMC")
Hope this helps