They unscrew, but not the whole thing. The spade actually goes between the bracket looking portion. If you are trying to unscrew the entire thing you will break it. Just unscrew from the top of the connector. Should unscrew pretty easily,
Speaker binding posts with plastic covers
My Krell amplifier has speaker binding posts with the clear plastic covers. Apparently these are for EU safety requirements. I want to use spade connectors and have no idea how to open these covers. I’ve wrestled with them but they don’t budge. I don’t even know whether they unscrew or pull out or whether there is some other method at play. Does anyone have experience with these?