By explaining something I occasionally experience as a mastering engineer I think I can help people understand some of the detrimental issues that relate to the loudness war in an easy manner. I will often send a master to a client and they will then say the track sounds excellent but they have had a listen to the track and it is not as loud as “X” as a reference. Firstly if loudness is an important factor it is always a good idea to provide a reference track so that the mastering engineer understand this is an important aspect of the audio mastering. My response to the client is often one which explains the non existence of a “loudness button” that exists independently of overall fidelity.