It's like reverb, but more subtle. It's inside the music, not laid on top like reverb. I think people think it's in the recording, the actual sound of the instrument. It's a sound we are all accustomed to, so we don't notice it until it's gone. I have read that silver also rings, but less noticeable, but this may be the cause of the silver fear many audiophiles have - too much detail, tizzy, etc.