Just a couple of facts to consider on this topic:
1)For voltage increase from 100 V to 120 V, that's 20% increase
2)For an inductive load, i.e. the power transformer of the power supply, an increase of impedance from 50 to 60 Hz, that's an increase of 20%
So, the current draw by the transformer remain roughly the same regardless of it being powered by 100 V 50 Hz or 120 V 60 Hz.
That's of course, just based on current, other factors that must be considered:
- The 20% higher voltage, would typically mean the DC (rail) voltage will increase by 20% as well, so one has to understand this and make sure that higher voltage is still well with the block/aka storage capacitors.
- Other voltage sensitive parts (most unlikely not an issue, just a cya remark).
Based on the above, for a low output amp such as the Luxman 509Z, it is hard to imagine the caps rated voltage could be an issue as even the popular 60 V rated caps would provide sufficient safety margin for the 20% higher incoming voltage. Even AVRs, those power supply block capacitors are usually rated 71 V or 80 V (flagship class such as the Denon AVR-X8500H).
Still, it is an expensive device, so I would urge the OP to contact Luxman, but again, ask the question skillfully to avoid getting a cya type of response.
