Using Japan 100V Accuphase amp in US 120V. Safe?

I agree with Atmasphere. Don't run it at 120V. A good analogy would be running a car engine 20% past the redline for extended periods. You can use a Variac or a Variable Autotransformer. This is a transformer with 120V input, and 0-120V output variable.

I had bought a 100v version of the F 25 Accuphase crossover. I had also been told that this was OK for 120v and have been using it that way for nearly a year.
However, prompted by this article, I took off the bottom plate and their is a guide, as stated by Alan Hsu above, which has a legend adjacent to the power supply leads that shows how to exchange the leads to get different voltages. In my case, it was to exchange the positions of the yellow/orange wire and red wire to get 120v operation rather than 100v. The leads were quite similar to the illustrations at the site shown by Alan above. I am not concerned by warranty, because I am sure my unit has none anyway since it is a labelled 100v version in the USA.
The unit never actually ran too hot, but it was warm before, and is cool running now. The balance of the sound shifted slightly, but it always sounded great, even at 100v.

Has somewone experience running an Accuphase amplifier of 120V on a 230V net, with a transformer 230V - 120V?

It's not just the question of the warranty.
If you have a problem with an Accuphase product bought in another area, they won't even work on it !
It happened to me.
Accuphase refused to repair my preamp, as I didn't buy it in the country I live, though I had bought other expensives items in my country ! It was in 2004.
As it was not too difficult a problem, a private engineer has been able to fix it.
Otherwise, the only solution is to send the outfit to the country it's been originally sold.

is it still easy to change by technician new Accupahse cdplayers from 100V to 230V ?