@rogerhifi, I also installed the MDx upgrade board in my M21 DAC and it plays perfectly. Based on your sound and distortion issue, I wonder if one of the cables that was removed and replaced are not tight or connected correctly.
When I installed the MXd board, we checked, and DOUBLE checked again, to ensure all cables and wires were removed and re-connected correctly. If possible, please remove the top and check that all cables and wires are correctly connected and tight.
The MDx board install requires the USB and AES/EBU connection devices (on the back of the unit) to be removed and re-connected. It is possible one of these is loose or not tight. Cables in this area also need to be checked.
I also do not understand that the symptom can be cured by turning the unit off and on again. I am guessing it could be a lose connection but I do not know.
And, yes, please call Joe at Bricasti for help. Please keep us posted.
When I installed the MXd board, we checked, and DOUBLE checked again, to ensure all cables and wires were removed and re-connected correctly. If possible, please remove the top and check that all cables and wires are correctly connected and tight.
The MDx board install requires the USB and AES/EBU connection devices (on the back of the unit) to be removed and re-connected. It is possible one of these is loose or not tight. Cables in this area also need to be checked.
I also do not understand that the symptom can be cured by turning the unit off and on again. I am guessing it could be a lose connection but I do not know.
And, yes, please call Joe at Bricasti for help. Please keep us posted.

