Simple lightweight high power amplifier circuit
You can try using Power BJT's. These BJT's are capable to handle lot more power than the simple BJT's.There are more number of Power BJT's available in market.They can surely handle 240V and even higher amount of voltages.Just google out for the transistor which can handle the power and voltage you expect.That's itIf you don't need good amplification,then you can use class A type of amplifier circuit.They are less efficient.Make sure to use a heat sink,because they'll generate lot of heat during operation.