Most U.S. electronics are UL listed for 120 volts from 50 to 60 hz. UL listings for computers, electronics, hair dryers, etc., take into account travel to 50 hz countries and, accordingly, manufacturers design power supplies to accomadate frequency ranges as vast as 50 to 400 hz.
Lower frequency power will mainly affect motors, i.e. your hair dryer will run slightly slower at 50 hz but still put out the rated wattage. But today's non-motor electronics and audio equipment will operate at 50 hz. As long as the transformer can handle the power, it'll work fine without a converter
As always, give the manufacturer a call just to be sure. Some equipment have jumpers to convert from 120/60 to 230/50 (easy to do) so all you'll need is the euro wall plug adapter.
Lower frequency power will mainly affect motors, i.e. your hair dryer will run slightly slower at 50 hz but still put out the rated wattage. But today's non-motor electronics and audio equipment will operate at 50 hz. As long as the transformer can handle the power, it'll work fine without a converter
As always, give the manufacturer a call just to be sure. Some equipment have jumpers to convert from 120/60 to 230/50 (easy to do) so all you'll need is the euro wall plug adapter.