110v vintage receiver to 230v US to France step up transformer

I'm guessing you have other components that you'll be taking that will also run off of 120vac? You will need to determine the total wattage of all equipment before purchasing a transformer. You may want to have multiple transformers, but that will get costly. Good links provided above. Some comments on AG are from people that have no clue, but some understand that it's not difficult. My personal suggestion is about double the power consumption of the receiver, which is 550 watts at 110-120vac, I believe.

On the back of the receiver, it will tell you the power consumption maximum. If you are driving 4 ohm speakers, I would go with about a 1000 watt transformer, just to have the added peak power when needed. If you don't listen loud, then you can get by with less. Most electronics, especially vintage, may have weaker filter capacitors in the power supply. I have found that LOW voltage is a problem for electronics in general. This is in addition to high or voltage spikes. Get a transformer the will keep voltage as constant as possible. You of course want something that is quiet for audio! More current is better for a supply, power = voltage X current.