Did you look at the compatible board list of that shield.
All of them are 3.3volt logic.
And the DUE isn't even on that list.
biancabiabn:
when I try to power the mega externally with a 12V PS the 5V regulator starts to heat when it's no current draw up to 55 degrees Celsius.
You should power a Mega (with it's linear regulator) with less than 9volt (7.5-9volt) on the DC socket, not 12volt.
With 12volt, Mega and shield (70+100mA) times the 7volt drop will dissipate >1watt in the regulator.
Making is sizzling hot.
Leo..