Grounding System Dissection

I recently was given the hard sell for a grounding system.  For those not familiar with the product, you connect spaded wires (of equal length and size) to the ground binding posts of the components in your system, then to the mystery box, which is then plugged into (or screwed into the center screw of) the same AC outlet where the connected equipment is plugged into. 

The alleged purpose is to decease noise when music is playing.

This reeked of simple "star grounding" to me and unnecessary in the era of three prong plugs.  (Your third prong -- the one at the bottom -- is the ground and grounds directly to the chassis of your equipment already.)

I do note that they wisely said "the same plug" as your equipment -- this is so your new ground does not allow a circuit breaker/fuse to remain open in the event of disaster -- catching stuff on fire and/or electrocuting you.

(The above is why I cringe when I read about people putting in "extra" grounds outside of their circuit box --- or hooking up to a water pipe or whatever.  Don't do that.  It's a violation of your electric code for a reason.  It literally tricks your breaker into not closing.)

What is "star grounding" you might ask?  Well, I deal with it in industrial plants.  Sometimes you have to have multiple grounds in a facility.  Grounds are not all created equal -- in fact, none are, even two plugs in your house.  You can get a differential between your grounds, causing all sorts of problems (e.g., hum in audio).  So you try to connect all your things (by the same length of wire) to a common ground point -- that looks like a star in the end from all the wires coming out.

Anyway, I cracked open this many thousand dollar box -- and low and behold -- each plug fed into a carefully disguised (er, "proprietary") 120V/15 Amp Shottky diode.  (These allow current to flow one way -- the anode (positive side) was toward the equipment.)  and then to a common (aka "star") point that was then plugged into ground. 

My theory of the purpose of the diodes would be too prevent unwanted communication between components (and I guess noise).

Grand total cost with deluxe parts would be about $50 on a bad day and anyone could make this, so I obviously didn't buy it.

But do these things do any good?  Unless there is induced current going into the cabinets, there shouldn't be any signal being carried in the ground at all.