Warning: Unlike other Arduino boards, the Arduino Due board runs at 3.3V. The maximum voltage that the I/O pins can tolerate is 3.3V. Providing higher voltages, like 5V to an I/O pin could damage the board.
The DAC outputs go from 1/6th of Vcc to 5/6th of Vcc and are extremely fragile (well
that might just be DAC0 which is also a wake-up interrupt pin leading down into the
1.8V core). Thus you cannot echo an ADC read voltage directly on a DAC pin, you'd
have to amplify it with a rail-rail opamp (a good idea anyway to make the output more
robust).
The chip is using a 1.8V CMOS process, only the I/O drivers are 3.3V, and they are
close to the limit, so take care, you have been warned.