Ground connections on gryphon preamp

Hi all,
I have a Gryphon Belcanto Pre amp, which has a seperate ground connection on each channel. It looks similar to the ground you get on tuners. What is this used for? are there benefits of it use? I figure it must be there for a reason?
Thanks in advance.

the grounding post is to allow the use of a seperate true ground - a copperpole in the ground -. Much better that AC ground.