Well, you probably won't be able to drive the motor directly, considering the DAC can only source a few mA to the motor. The maximum current draw from your motor will occur while it is stopped because the motor must also overcome windage and frictional losses. This method requires a dual power supply provided you would like to drive the motor in two directions, otherwise, you could use the DAC to drive a transistor which would drive the motor. I have attached a method of controlling the motor in a bi-directional configuration using the DAC and a couple of transistors. Note: The transistors selected must be able to handle the stall current of your motors as a minimum, otherwise they will blow out.
Hope this helps,
Tim
