I knew if I put that drawing up that everyone was going to fixate on that aspect. It was just a simple quick illustration that was partially borrowed (I just changed a few details), and since my question wasn’t about the grounding of those wires, I was hoping it wouldn’t become the focal point of the discussion. FWIW, I am grounding my xlrs at the connector, and I’m not using a plastic enclosure.As I mentioned before pin 1 of the XLR should be tied to the ground immediately where it is mounted onto the chassis. The scheme JMAN has given in his diagram is already a bad idea in terms of pin 1 earth connections.
If he is using a plastic enclosure (which is even a worse idea) then he may need to do that, and yes keeping the earth wire as short as possible would be a good design practice but not hugely important if it is a few inches longer.
As for the screens for the signal wires used inside the case the situation is slightly different. Good practice would be to tie the screens on one end, and at a single point at the chassis/earth point near the IEC, so that all noise currents would run towards that point. The mistake would be to earth them on varying chassis points within the case. Now you have varying ground paths and that is an invitation to a problem.
This relates more directly to my original question (I don’t mind that the discussion has gone elsewhere, but I like getting opinions on what I was actually asking too).
I feel like I’m getting mixed messages in this thread, though. Based on what has been said, it seems that screened signal wires are useful for capacitive noise but not magnetic (which honestly was news to me...why have I been wearing this tinfoil hat, then? Joking!). And my AC lines — my main noise consideration — are going to be on the magnetic induction side of that, so screened wires won’t provide much useful protection. Instead, tightly twisted pairs (along with, I’m assuming, good spatial arrangement) will be the better option.
Does this mean that twisted pair shielded wire is a bad idea, though? I have plenty of that, and I figured it would provide extra (if, I guess, unnecessary) insurance. I can go either way, though.