The NXU-2/A uses balanced audio on the input. If, instead of connecting to both balanced input lines, you connect your audio to one audio input and ground, you'll get the effect described above. There is enough leakage in the transformer to get some audio through, but it won't work properly. The solution is to ground one side of the NXU-2/A balanced input.
Why can I barely hear audio from the device connected to my NXU-2/A even though the levels are turned all the way up?
