Tell me about your loopback test, that was successful. I presume you used line-out to line-in?I have performed a successful loopback test. The issue I am having is during the next phase "level check". The device is producing pink noise through my a/v receiver just fine but there is no signal being generated through my ecm8000 microphone. I can scream into the microphone and no green signal light. There was a green light during the loopback test so I know the channels can take a signal but nothing happens when I try using a microphone.
If so, you realize that the loopback (in this case) is not utilizing the mic preamp. So this, or the microphone, or its cable must be at fault. Have you tested the mic anywhere else? Do you have the phantom voltage turned on when using the mic? Have you bypassed the cable and plugged the mic directly into the unit?