COnverting Audio Equipment Voltage From 110 to 220

I have numerous audio devices that I plan to take with and use in Germany. Years ago when I first entered into the audio business I could purchase audio in the military audio retail clubs. There, they sold almost exclusively audio equip with user-switchable voltage. I knoe that these items also were built to handle 50/60 Hz where applicable. I wish to know if I can purchase the internal transformer for my AVR receiver, tube amp, tube CD, SACD player, etc.