Amplifier voltage conversion

I am interested in buying a processor-amplifier combo in the US and taking it to Europe, i.e. Anthem D2v+P5 or Classe SSP-800+CA-5200. Now obviously there is a voltage and hz difference between Europe and US and transformers seem to be a no-no from a sound quality perspective unless one goes for industrial/medical instrument quality products.

Now there is the option of voltage conversion by various audio shops. Now I am not veyr techie unfortunately and hence I would like to ask if anybody can explain me whether this voltage conversion has any negative benefits and what exactly is changed?

I mean is it the whole transformer that needs to be replaced (unlikely some audio shop can do that) or is it just a fuse or a switch(can even be done by a knowledgeable amateur without degrading sound I would assume)?

If it is very different between manufacturers I would be in particular interested in Classe and Anthem amplifiers and processors.

Thank you for you explanations!
I would purchase in Europe and make sure the product switched to 120/60Hz for use in the U.S. I've taken product to Europe and purchased a down converter for smaller electronics. It worked fine, but they were not upper end electronics. I took a Proton 300/301 table radio combo with a Kyocera 810 cassette deck. No high voltage/amperage demands.

You will also have the customs headache when the product arrives. They will assess value and you will need to show that you did not sell it while in country.
Actually I am interested in buying in the US and taking it to Europe hence having a 230v version but sourced from the US.

Even paying customs prices for many products are still so much cheaper in the US that some 20% still is very doable
I have done it on a number of occasions, both a CJ Premier 17 and Karan K180. It is doeable and I had the voltage changed in the UK. The CJ ewas easy, they are built for both markets. It is simply a matter of changing the taps on the transformer, to change the voltage. Likewise the Karan
I tried it for a Viva Solista tube amp, not so good. The US voltage was doubled to what was then the European standard 220volts, not the UK's 240+, after blowing several caps, it had to go back to Italy and took a year, to have UK specifeied transformers. An expensive mistake.
The answer is then, it depends on the amp. Some are OK, some not. Tube amps seem more of a problem, perhaps because of the large plate voltages in output tubes