My first experience of grounding was the jitterbug a active device for computers it helped give a darker background
I arrived a year later than Martin and Mike and I tried a variety of boxes on my digital side before settling for the RTZ 3 that now just helps with ground plane noise from the DAC
I have a industrial estate close by which can affect my mains quality. I recently did a lot of detective work with the help of Tony from Coherent who encouraged me to have a systematic approach to my mains issues
I found grounding the mains had a massive lift on my noise floor This was not subtle at all but out of my price league If I could get a sense of the same improvement I be happy
I talked to my friend Vic about building a grounding box but looking at the price of materials it seemed a better bet to buy 3 boxes from China and get Vic to build me a bigger box from the 3 I figured that having more ground for the noise to go to would be helpful
However the boxes arrived at different times, so I put the boxes in the system I used the small one from ebay first and put it on spur which feeds the digital side and Behringer. I then got the one I linked in for Jules on what goes inside a grounding box. This was the biggest surprise as I had to lower my bass from 93hz to 56hz. I can easily adjust the bass crossover on my system and had to lower the bass as the Temples were driving the Kefs better
This had a impact on dynamics rather than fine detail and 3D imaging. The Temples are running on ring mains so this is plugged into a spare.
I then added Martins latest box on the spur and moved the small eBay box to the ring main which meant I had to adjust the crossover to 47 It added more depth and 3D imaging I think this is due to the bigger box being better than the ebay box
In summary
On digital equipment more depth in my system
On the Temple which is class D and uses a linear power supply with supercapictors I get more clout better bass and impact
I have more mains issues than most people so people's experience are likely to be different to mine

Try and report back. My guess is more noise going to ground so a bit more depth or impact I kind of do this on the ring main with 2 grounding boxes plugged into different sockets and both had a measurable affect in the context of my system. But it slightly different to what you saying so not sure yet. But read this space in a few weeks and I confirm or deny

Agree unless it has a separate earth rods like the RTZ 

Even snake oil has some purpose.

I can't vote as my choice is not there "I haven't tried one because generally commercially they are TOO expensive, but will when I can make my own and do some listening tests."

Can anyone advise if they have built there own where and what they sourced to put into it? 

When I looked into this it worked out pretty much the same to get a Chinese box and far less hassle

Agreed - the Chinese boxes are not expensive.

Warning - the connecting cable makes a big difference. It needs to be able to pass high frequencies. A spare bit of green/yellow earth wire is not ideal.

I am confused.

The premise that what is going on with these boxes is that it provides whatever is being connected up to with 'its own little piece of mother earth'.

The component parts that are required to make this little piece of mother earth in a box are expensive and/or dangerous.

All you need to connect them is a bit of wire.

So, why not connect the bits of the system up in the same way, but to the actual mother earth? It ought to be just a longer wire and a bit (or several bits) of pipe knocked into a flower bed or lawn.

I didn't mean to suggest that one would use a mains earth point. I thought people were using these things as passive devices

I feel a new system diagram coming on Martin - how many grounding boxes do you / will you have?