Difference Pi3B+ & Pi4

[roderickvd]

I also remember that the RPi 4 generates more EMI than the RPi 3B+, but on the other hand it also has a quieter USB bus. Pick your poison. If it were to concern me - and it does, to tweak that last 1% out of my set - I look towards some isolated outputs. An external USB isolator, optical SPDIF, AES, IanCanada isolating HATs... again, pick your poison :-)