Hmmmm, don't agree, just swapping out a 110V transformer for a 240V effects the whole circuit IMO. The power transformer is a very important part of the tuning of the amplifier; anyone who has tried several different VA ratings for their power transformers will tell you that for instance a 200VA transformer may provide a liquid midrange but thin bass, a 300VA transformer may provide more bass but worse midrange. Naim had a lot of problems when their original transformer manufacturer went out of business, they struggled to achieve their signature sound with other manufactures power transformers despite being rated for the same outputs; geometries, laminations, wire size etc all play a part in the final sound of an amplifier and when one looks at two transformers identically matched on paper they can prove quite different in practice. Some manufactures run their magnetics at a long way beneath saturation and at low core losses, others don't. Tamura Iron is going to be a lot different to Chinese 'Dick smiths' iron!
It has already been established that vintage chokes for the Killer DAC produces a better sound than their built down to a price from scrapped Japanese cars chokes, the same if not even more importantly applies to the power transformer as all an amp is after all is a modulated power supply. And lastly, the American mains runs at 60Hz whereas here in Oz we run at 50Hz, don't think this makes a difference, well IMO it does as the whole circuit would have been tuned around it.
And on a final note, amps brought over from the UK do not always work correctly here in Oz, well let me qualify that statement, specifically valve amps. The heater voltage on my 211SE amps instead of the correct voltage was higher due to the rise from UK mains to Oz mains, don’t make a difference, ha ha well maybe YOU have not tried it.
V