From web:
Amps – This is the measure of how much electricity is flowing through an electrical line, which is like the amount of water flowing through a hose.
Volts – This is the measure of how strong or the force of electricity flowing through an electrical line, which is like the pressure of the water flowing through a hose. Most devices in the US are rated at 120 volts, with large appliances sometimes using 220 V, like clothes dryers. Effectively, this means those appliances can suck more power per minute than appliances rated at 120 V.
Watts – This is the result of multiplying amps and volts together (amps x volts = watts), which is the working capacity of the electricity.
If the answer has to be 600 W, does running on lower Amps mean it's maybe running on higher Volts ??