I'm trying to figure out which jacks on my PA amp are shielded and which aren't. To this end, I was looking at the block diagram in the manual. I'm new to reading block diagrams, but it's obviously a useful skill to have for understanding signal flow in a pro audio environment.
Can anyone tell me what the symbol below means? (Just in case the image ever gets separated from this text, it's the one that looks like a wide, slanted triple-tined fork pointing down, under both the hi Z and low Z input jacks.)
Even better, could anyone point me at a resource of pro audio block diagram symbols? I was surprised to not be able to find this online.