I'm sorry, I don't mean to mock anybody, but people go to incredible lengths to optimize and choose cables, connectors room treatments, racks and any of the hundred and one things affecting sound.
Some items are pretty...shall I say....esoteric? The differences in cables, some would say is pretty small while others call it titanic.
I'd say that any tweeter hiss is on the intolerable side.
A BUZZ from the tweeter? Shouldn't that be a HISS? I'd expect the BUZZ thru the woofer.
Start going thru the list by first disconnecting everything and if the hiss goes away, reconnect 1 item at a time till it returns.
This is the worst thing to track down. I'm betting on the Sat Box, which has lots of RF circuitry and are notorious for spewing it everywhere. My sat box is a good 3 or 4 feet from anything stereo related.