Hi Blumein 88
The restrictions of the Shannon /Nyquist theorem were that the first digital sampling occur at twice the highest frequency determined. Hence sampling was sadly determined at 44.1 khz which dictated that the highest audio frequency could not exceed 22.05 khz, or equally it was thought that 22.05 khz was beyond our perception of hearing which determined 44.1khz as the original CD sampling rate.
As such a restriction was created - that equipment manufacturers then sadly feverishly followed.
If we view before this, Quad as one such manufacturer, the 303 power amplifier measured 30 hz to 35 khz
and the amplifier following it the 405, measured 20 -20khz
There are many viewpoints that the 303 was /is the better sounding amplifier - half a tick I think for bandwidth being actually why
David passed away in 2002, his main body of work was in companding seen in the DBX products,but in later years he founded Earthworks
https://earthworksaudio.com/about-earthworks/ His same philosophy can be seen to push the boundaries of what we can perceive in audio. THAT Corporation have continued with his licensed ideas
http://www.thatcorp.com