Step down transformer, 220V to 120V.... Isolation transformer being the best way, auto-transformer the cheaper way to go.
Bigger problem may be the AC frequency (Hertz) of the power transformer of the VT60. Look on the back of the amp where it says voltage and Hertz. If 60 Hertz only and not 50/60 Hertz the 60 Hertz only transformer on 50 Hertz mains will be mechanically noisier, run hotter, and will fail in time.
Bigger problem may be the AC frequency (Hertz) of the power transformer of the VT60. Look on the back of the amp where it says voltage and Hertz. If 60 Hertz only and not 50/60 Hertz the 60 Hertz only transformer on 50 Hertz mains will be mechanically noisier, run hotter, and will fail in time.

