[LAU] Ground lifts, TRS, etc. to PA? USB/other signal crossover to audio?

[Ralf Mardorf]

PS: We should keep in mind that it's very important how the gear is
designed, what components are used. Some legal mains jacks don't provide
grounding.

https://en.wikipedia.org/wiki/File:Euro-Flachstecker_2.jpg

Gear signed with this logo

https://en.wikipedia.org/wiki/File:Double_insulation_symbol.svg

usually is not connected to ground. Attention, _at least it's not
allowed to connect ground to the case of a class II device_!

Metal case, build in power supply, Europlug
http://www2.yamaha.co.jp/manual/pdf/pa/english/mixers/RM602E.pdf