speaker to pc

Hi.I have 2 vintage Radionette TK 18 S but I`m a bit confused about the specs. This is what it says on the back - Impedance = 40 OHMS Max continuous load = 25w Max peak load = 40w Input (at 96dB) = 4w Frequency range = 50-20.000 Hz What wattage amp do I need run them from my pc? Thanks.