I use Plixir balanced isolation transformers for the power conditioning of my Devialet 1000 Pro. The isolation transformers don't hum. I've not tried the isolation transformers with a 220 or 440 Pro.
However, I have an LG OLED TV, which *will* cause the isolation transfomer to hum if I connect the TV to the output of the isolation transformer. So my TV is connected via a regular power conditioner.
Transformer humming is usually caused by a DC offset it the AC supply.
You might want to try the ifi DC Blocker to see if it helps your case - although it doesn't fit directly into the IEC power port of my Devialet 1000 units.
https://ifi-audio.com/products/dc-blocker/
However, I have an LG OLED TV, which *will* cause the isolation transfomer to hum if I connect the TV to the output of the isolation transformer. So my TV is connected via a regular power conditioner.
Transformer humming is usually caused by a DC offset it the AC supply.
You might want to try the ifi DC Blocker to see if it helps your case - although it doesn't fit directly into the IEC power port of my Devialet 1000 units.
https://ifi-audio.com/products/dc-blocker/
Devialet 1000 Pro CI - AQ Diamond AES RCA-XLR Link
PC - ifi iDefender+ - FIBBR Alpha Optical USB + "Studer 900" LPS - Singxer SU-6 - AQ Diamond AES
PSB Imagine T3 - AQ William Tell Zero / Tornado / DBS Level-X - PliXir Balanced AC
