What is the best AC Voltage step down converter?

Japan uses 100V 60Hz/50Hz. All Amps/Cd players are designed for both 60Hz and 50Hz. You can change the voltage from 100V to USA 115V by moving the Jumper inside.
If you want use a transformer the best ones are
Nisso NDF-1500U or Sanyo both made in Japan.

Thanks Renjy651..checked out the Nisso and Sanyo online..very impressive..

Nissyo NDF-1500U It can be purchsed from a Japanese store in New York for $200. I recommend this one 1500 Watts. Sanyo is same in power but bigger in size.