I don't think the 50/60 Hz will make a big difference (if anything, less power is consumed at 50 Hz, e.g. with motors).

However, voltage in Frankfurt is 240 V, not 220 V. That's about 10% more volts or 20% more power than your rating. I never thought this would cause a problem with modern power supplies, but since I've seen the power supply of my new Roomba vacuum cleaner I'm not sure modern power supplies are common in the States. It looks like a contraption from the 80ies.

HTB.