Well, I find I just got fooled by A+. FYI, to use the DoP mode in A+, the volume has to be placed at the maximum position. Otherwise there is no sound.
I had some problem playing DSD with my MC3+USB. I use Audirvana+2.0 on Mac and manually select DoP mode(the automatic detection in A+ failed to recognize Mutec's native DSD capability). However in the end the MC3+ could not generate a sound. It doesn't get DoP input and nothing was illuminated in the "clockin" section. It works so good with PCM streams so far. My DAC does not support DSD so I need MC3+ to do the DSD/PCM conversion. Any help will be appreciated.