What brands are frequency 60hz specific ?

When we move to Europe or Asia, in almost all countries there power voltage is 220V/50hz.As I know for some brands( Krell,Levinson,Martin-Logan) only using a voltage converter (220 to 120V) for US version gears carried there will be useless for those brands are FREQUENCY 60HZ SPECIFIC.Though fed with 120V( converted from 220V there),they'll sense the 50hz there but not 60hz they're fed originally in North America then those gears don't work.
Anybody knows any other brand also FREQUENCY 60HZ SPECIFIC?
The PS audio P300 has the ability to input either 120/220 and change the frequency (50-120 hz).

The P600 has more power with the same abilities.