I did more searching. There are quite a few days the balanced isolation transformer (versus linear?) makes a bigger difference. I guess I will try a balanced one.
I see some isolation transformers on AliExpress. Although it seems the isolation transformer mainly consists of a giant toroidal, I don’t know if I can trust those. Like the one below, there is not much information and there is no picture of the inside.
C$ 143.63 7% Off | U.S 500VA Toroidal balanced isolation transformer 500W AC isolation power supply processor With 6 outlet socket
https://a.aliexpress.com/_d6XNC5l
I see some isolation transformers on AliExpress. Although it seems the isolation transformer mainly consists of a giant toroidal, I don’t know if I can trust those. Like the one below, there is not much information and there is no picture of the inside.
C$ 143.63 7% Off | U.S 500VA Toroidal balanced isolation transformer 500W AC isolation power supply processor With 6 outlet socket
https://a.aliexpress.com/_d6XNC5l