The Audya power label states 100 - 240 volts AC 60 - 50 Hz.

Its a switched power supply on board and therefore can be used anywhere in the World, I am not saying that Yamaha do this but I would think the days of making equipment one for USA and another for Europe are gone, technology has moved on. Still look on the label before you plug it in.

This is what it says in the T4 Manual below:

Make sure your Tyros4 meets the voltage requirement for the country or region in which it is being used.

I can only think that Yamaha make KB for each voltage, there is no sign of a dual voltage, but please look on the back of the KB and the plug on the end of the lead might give some indication, the label will without doubt tell you,it may be also a case of a person going to another country and buying a KB and taking it home, like Skude did with his Audya, the Audya would work because its multi voltage and freq. LOOK AT THE LABEL PLEASE OR BOOM!

Here is the T4 warning

Make sure your Tyros4 is rated for the AC voltage
supplied in the area in which it is to be used (as
listed on the bottom). Connecting the unit to the
wrong AC supply can cause serious damage to the
internal circuitry and may even pose a shock hazard

Tony

Thanks for your help tony. I was told the tyros 4
Would require a step down transformer to operate
In a 240v 50hz country like mine. Does this mean
That the speakers will have to be from the usa...
Because if I bought the tyros 4 factory speakers from
My country it might destroy the keyboard?

You need to look on the equipmnet what it says, it will always have it stamped on somewhere, the speakers have a low voltage transformer, the input voltage will be on there too, just check it, do it yourself and don't chance it if you don't know it will be expensive if its wrong, look on the kit.

Best of luck, luck doesn't come into it BTW.

Tony

The KORG Triton series has a label for 110 and also the M3 but still works for 220 so, maybe Yamaha is the same?