I have started my next project, a bucking transformer. I initially had problems finding a suitable transformer until I remembered an old 13.8v power supply I had for powering an AM CB radio back in the late 90s. I dug it out of the garage and tested it's output, 19 volts, which would make it ideal for use with 220v devices. However, quite a lot of these Chinese tube amps are 230v and I also worried that I would suddenly have a use for that power supply so I opted to search for another transformer. This is what I found:
"Custom audio 64W multi-purpose power transformer Multi-voltage input secondary multi-winding output voltage adjustable" https://www.aliexpress.com/item/32982855405.html
The 'B' version seems to have all the right specs to reduce the voltage to 220v and 230v except for the 2 amps output. I would have thought that the amperage would vary across the output voltages so if 32v is 2A, then the 20v and 10v output I need would be 3.2A and 6.4A respectively? I went ahead and ordered the transformer anyway and plan to use this schematic that I modified from here https://sound-au.com/articles/buck-xfmr.htm
Proof of concept. Mains voltage was 242VAC at the time of testing: