100 years back and 100 from now Audio Equipment and Delivery ?

[Light Dependant Resistor]

Many answers are possible.
Here is an excellent read on the history of the Gramophone record http://en.wikipedia.org/wiki/Gramophone_record
but 100 years from now ?170px-Caruso_with_phonograph2.jpg

[Macca]

100 years from now...the world will be a tougher place. There will only be two currencies. The two basic essentials it seems mankind cannot live without despite the march of progress: Tinned food and vinyl records

[The Grand Wazoo]

Here is an excellent read on the history of the Gramophone record

There is something on the subject in The Knowledge:
The Turntable and the History of Recorded Sound