good point. the voltage output from an adjustable switching regulator will sag with relation to the input voltage.
what happens if we connect one external power source to the 2.1 round connection and another external power to the VIN connection? Will the Arduino get too much power and break or will it just choose one? Just wanted to know.
Nice. The reason I said to take the 5 output volts and put it on the VIN pin is- that the Arduino's voltage regulator will not do anything as it's already 5 volts.
Am I mistaken?