https://en.wikipedia.org/wiki/Distribution_amplifier

An Audio Distribution Amplifier also known as: a press feed; a pool feed; a media feed; press box; or an ADA, takes a single audio feed, usually a line input, but it may be a microphone input, and outputs multiple line or microphone outputs. This can be done using a passive feed, where the signal is split among the outputs, or as an active feed where the outputs are amplified. The primary use of the Audio Distribution Amplifier is to share a single audio feed with multiple members of the press pool. Thus the names press feed, pool feed and media feed.[

A Video Distribution Amplifier (also known as a distribution amp or VDA) takes a video signal as an input, amplifies it, and outputs the amplified video signal to two or more outputs. It is primarily used to supply a single video signal to multiple pieces of video equipment. It adjusts the amplitude of a video signal to compensate for loss of signal in a video distribution system. Extending the distance of the video signal is the main purpose of the VDA.

How the earth terminal on a TN-C-S supply can be at a different voltage to the true Earth.

As the neutral and earth conductor are combined outside the installation, current in the neutral causes a voltage drop, which results in the earth terminal having a different potential (voltage) to the true Earth outside.

information & resources about transformers and splitting line level audio signals.

#021 Transformer Isolated Passive Mic Splitters!
https://www.youtube.com/watch?v=K_gl1RIXVFU

In this video we take an inside look at passive transformer isolated microphone splitters and how we use them in the real world.

If you maintain all original earth connections, then adding another one is more likely to induce ground loop hum than cure it.

This paragraph says it all to me: “If you can effectively remove or drain away the pollutants, stray magnetic currents and impedance fluctuations before they contaminate the sound, there becomes no need for the active synthetic filters & other such devices commonly recommended by many manufacturers. Our ground box’s are surprisingly heavy, feeling very solid and robust. However we do not talk about the specifics of construction, materials or any of the development technology housed within any of our products, especially the range of Ground Boxs.”

FFS, they can’t even spell ‘boxes’. And if anyone can explain to me how these will ‘drain away pollutants’ I’d love to know.

Total and complete bullshit, without even bothering to try and explain.

Very good point Serge but people see what they want to see and hear what they want to hear

A few years back a friend of mine bought some very expensive P*D cables, forgot the name but it was something about 3-4k per meter, after a while he wanted better connectors and opened the cable. Guess what he found? Belden computer cables, thin, cheap, surrounded by big foam. He was really mad about that… the question is: Do you really want to know what you have bought?

Syntax, I remember someone posting pictures of the inside of the Transparent “boxes” that are on their cables and it was just silicone glue and I think a resistor.

Bill Withlock Ground Papers

An Overview of Audio System
Grounding and Interfacing
https://centralindianaaes.files.wordpress.com/2012/09/indy-aes-2012-seminar-w-notes-v1-0.pdf