You could try
Plug In RF Router UK | System Grounding | Russ Andrews Accessories Ltd
There is also a European version.
More reading on grounding
I have met the owner of Puritan ( Mike ) many times really nice guy and honest, great products.
In UK, the "plug in" version does not seem to be supplied so why I have posted a link to Russ Andrews who make other products.
I tried an earth wire 10 mm one wire connected to a Power supply for a DAC then in to a ground rod as an experiment FOR A FEW MINUTES ONLY.
DO NOT CONEECT ANY OF your equipment to a ground rod without a RF router of some type.
Grounding - Safety Fundamentals (1hr:13min:19sec) - YouTube
Moving on.
Grounding my system with one wire via a ground rod as above made a pleasant surprise, bass improved and treble less harsh so went all in for a full blown system with 2 x 3 meter ground rods 21 metres apart with 16 mm earth cable.
One rod measured 18 ohms two rods 10 ohms.
I must admit there was not much more improvement with the full blown version that ended up being quite expensive various cables and all equipment connected.
My advice is try a ground rod with one wire before you purchase a RF Router.
Hope the above helps......