The essence is that its music from the soul of the performer/s which has a profound impact on the listener
This particular type of music compels the listener to get more of the stuff to fuel his habit.
It is not possible to replicate the music simply by performing the tune/song as this particular music has a quality which comes from a particular era and the manner in which it was recorded, arranged and produced is peculiar to that era.
The music has a certain dignity which is borne of the fact that most of the recordings were not commercially successful and thus neither heard nor appreciated by the majority of people and what identifies devotees of NS is their recognition of that dignity in the music and the feeling that they are not buying into the mass exploitation engineered by big business in the music industry.
The profound impact that the music has on its devotees,is denoted either by an urge to own a recording of the track and then search for more, or to share their appreciation of the music with others by playing it over a PA system or by interpreting and expressing the music in a particular style of dance influenced by the style of the artists themselves and also by the dance styles of the era in which the recordings were made.
Insomnia's a b*stard innit.