Integrated amp, best conversion 220 to 110 volts?

Greetings all. I have a Marantz integrated amp from Europe that utilizes 220 volts and want to convert it to operate on American 110. What's the best way to go about this?
Replace the internal toroid or add an external step-up? If the former, where can I obtain a superior, audio-grade (perhaps oxygen free copper)transformer?
Many devices are built with a transformer that has taps for 220 and 110V. In that case all you need is a service technician that opens the unit and changes the taps from 220 to 110, and you are ready to go. Check if your Marantz is made like this. I have had this done with Rotel, McIntosh, and know Bryston is the same. It cost me all of us$50 per unit. BTW, initially I was told by McIntosh I had to change the torroid in the amp...fortunately had a reliable service tech who said otherwise.

Let us know if this works.
Thanks for the tip, Lewinskih01. There aren't any extra wires coming off the torroid, however -- all wires are being utilized. This suggests to me that I need to replace the transformer.
Just because all of the wires are used, doesn't mean it isn't convertable. A transformer designed for both 110 and 220V operation will have 2 primary windings. When wired for 220, the 2 primaries are in series and when used for 110, they are in parallel.
Aha. OK, thanks, I'll take it to an audio tech to check it out!
Audio tech says the torroid is custom made and there aren't two primary windings so I have to either replace it or use a step-up xformer. Suggestions?
That was fast !!!!
So where can I get a reasonably priced audio-grade torroid or other xformer for the amp?
Do you own your own house? If so, what are your thoughts on running 220 from the dryer/range circuit to the room where you want to run the amp?

When I returned to the USA in the early 90's after having served in Germany for a few years, I had some Soundcraftsman amps (A5002) I needed to get converted to 110. I found a tech and he was able to do it. Since then I have returned to Germany, traded one amp and the other is waiting to get refurbished. These are heavy beasts and the transformers inside are huge. They have cooling fins on the outside and two man lift handles, ha.

If you search ebay you will find plenty of transformers that are capable of converting 110 to 220 volts. I know of people who have purchased multi-power converter transformers capable of 2000 watts. The ones I have seen on the Internet that are multiple voltages, instead of two, are mostly made in China, India, Japan, or some other country.
Yes, there are plenty of transformers listed on EBay but are they "audio quality"? I doubt it. Power supply is critically important; it all starts with power...
Nope, need to replace the transformer. The question is: Where do I get a reasonably priced AUDIO GRADE torroid?