The actual power output at the spot may be less, but from the initial power
onput power is dissapated in the transformer windings. But by the ohms law
formulae yes you can have 50W output for 12V or 230V but there are different
resistances in the circuit.Low Voltage Halogen Spot Lights use less
energy than mains voltage. How can this be? Do they defy the laws of
Physics? 50w at 12V uses the same energy as 50w at 240V.