http://www.ebay.co.uk/itm/Audio-Grou...item3f7d4189c8

https://tinyurl.com/y8rwh533

I've no idea what a piece of wire attached to a croc clip at one end and
a piece of rosewood (possibly containing silicon wafers?) connected to
the chassis of your Hi-Fi item is supposed to do. Presumably nothing as
they thoughtfully add the following caveat..

"Pls note : We can't 100% gurantee the Ground box have the expected
effect, because it is Subjective feelings，Different person, different
device, different condition and enviroment can let the respond
different, someone respond the ground box with great effect, another
person respond the box with little effect"

Makes 'running in' speaker cables seem positively sane!