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

[Ralf Mardorf]

Fons, Dale, I didn't verbalised well. I wanted to point out that
completely interrupting the mains ground is extremely dangerous (I guess
I verbalised this part very well), but that not everything in a device
needs to be directly connected to ground (regarding to this I inartfully
expressed), connections to ground sometimes are done by resistors or
capacitors.