120V/60Hz to 230V/50 Hz AC

We are moving from the US to Germany and want to take our system with us: Belles DMC stereo preamp, Dynalab FT11 analog tuner, Hafler 220 power amp, Technics M44 cassette deck. Step down transformers are easy to find and relatively inexpensive, but such units change only the voltage and not the frequency. Units that accomplish voltage *and* frequency conversion are available but much more expensive, and am wondering how sensitive the above system would be to 50 Hz current. Does anyone have experience with this issue?
Contact manufacturers first, and ask if those units can be rewired for 230v operation. Most can.
See my previous responses to this question (I moved from the States to France twice). You will have no problems provided your equipment is not configured to work on 60Hz power only (newer Krell, Martin Logan, Mark Levinson etc.). In most instances a simple step down transformer works well.
The 60/50Hz is no problem, in Germany you can use Step down Transformers...or you can send your units to the Manufacturer for a European voltage change. Shouldn't be a problem.