Would it not seem if it didn't hum with the old DAC and the new DAC hums, that it is the new DAC's sensitivity to hum.
Likely the hum is not caused by either, but is the product of an ungrounded cable or sat system. Unplug the cable (COAX at the wall) and see if it goes away.
Likely the hum is not caused by either, but is the product of an ungrounded cable or sat system. Unplug the cable (COAX at the wall) and see if it goes away.