110V/50Hz equipment in a 220V/60Hz country.

I use a PS AUDIO power plant which solves the conversion problem in the first place and is a recommendation in the highest order anyway!
You also can use a very simple transformer - available up up to 1000 VA - which I did for my WADIA's before I had the PS AUDIO plant. No problems whatsoever, though some "experts" warned me of having major hums or similar surprises.
However, I would recommend having the power amps converted at the factory before moving.
Good luck!

I used a US 110V/60Hz Pioneer PD-54 Elite CD Player on a 220V/50Hz electric power system using a step-down transformer for a few years. The step-down, of course, reduced the voltage by half, but did not affect the Hz cycle. The unit performed without problem, but then the laser diode burned out. I do not know if this was transformer induced. There was also a degradation in sound quality, resembling the type of sonic deterioration produced by jitter. Because of warranties, and uncertainty about problems, I would have the manufacturer switch the transformers for you, if they can agree to do this for a reasonable charge. Some might refuse to do it at all because of sales policies. Otherwise, use the PS AUDIO power plant, or a quality step-down/step-up transformer (I use a CuestaSystems PowerSwitcher, but there are better ones).

What has been said above is largely close to the experiences I have made. I live in Europe and I am using Spectral equipment of 120VAC provenience. I feed the preamp, as well as other audio gear through a PS Audio 600, which is set to input 230VAC and will output US voltage. For the big amps I am using Equitechs (www.equitech.com) of sufficient wattage, which will also use 230VAC at their input, but deliver 120VAC at their output, with the added advanage of balancing the output, which means about 6db less noise in the powerline. (The Spectral Monoblocks cannot be inernally converted to a voltage different to what they were made for.)

I am in Australia (240v/50Hz), and have had some experience with your dilemma. With most US made equipment, changing to a different voltage has been thought of in the original design. Some make it extremely easy (I have a Rowland preamp with dip switches for different voltages), some fairly easy (e.g. Pass Aleph 3 required a jumper resoldering), a few will require a new internal transformer (if you dont want to use an external one). Almost every company I have asked will respond to questions about how to reconfigure their equipment. The rare exception being Spectral. I use a Spectral power amp through an external stepdown transformer without any problem. I am unable to say if the sound is degraded, but I am happy with it. Any equipment made in a 220/240v country is more likely to be easily changed (e.g. Plinius, YBA amps)

Thank you all for the responses.
Most of them have focused on the power amp,
I must admit I am just as worried about the CD and tape
player. Can the change in frequency affect the operation?
(this may be a very naive question, but anyway.)

Cheers, and thanks,