Thanks, I guessed that was because of the 2 pin plug (class II) but was not sure.Again - that can be quite normal. If you have class II (non grounded equipment), then any leakage (normally capacitive) of noise (including noise from the mains supply) goes to the chassis and has no-where to drain to. It can be quite a significant ac voltage, but very high impedance, so all it can do is tingle. There is no current capability behind. it.
Though it can be particularly strong when you have a bunch of class II devices connected together, and you get the combined leakage current of them together. My AV System with TV, AVR, Settop box, DVD player - all connected together, would be quite uncomfortable when I unplugged the antenna cable with a metal plug. In the day's when I had an antenna cable. You only need one class I (grounded) device in the mix, and you never see it. Everything drains to earth through that.
EG:
I don’t know if is due to leaking or something else, but my WiiM doesn’t sound good even connected by proper RCA to XLR cable, so I use my audio interface.
It has the advantage of reducing signal with its attenuator (analogue), so the volume of the WiiM remote can be nicely smoothed (normally goes on 32-33 steps from 0 to 100 but 8030C are so sensitive that was confined between 20 and 40 on many tracks).