The problem is not solved now. I thought I had solved it when I flipped the wall wart or more appropriately, theplug on the power supply. That seemed to do the trick. However i was using a different amp's FX loop. So now the hum is back. I did check out my cords and bought a Pedal Snake, which is really a grea thing for the M13....4CM with one line!
Anyway, it seems it might be in the amp. However, it is possible that the amp just doesn't :like" the M13. A friend on another forum had an issue with his RM50 and the M13. I am still trying things. Hopefully it is something in the amos FX loop as I really like the M13.