Power supply recommendation for Due needed

Using Arduino General Electronics
1

I am just putting together a list of parts and need a good source for the Wal Wart.. Does it have to be 3.3V or can it be higher??? What is the plug style? and is it center pin positive?

2

This page tells you pretty much everything:

3

Attention :
You can read this :

Summary
Input Voltage (recommended) 7-12V
Input Voltage (limits) 6-20V

But on the DUE board pics you can see that capacitors are only 16 volts max