[phuctan139]

Hi all,
 
I am a.. just a newbie in here, at first it is simple to me to buy a good headphone + amp and put it to my iphone and listen to music but now I just want to know more about the sound, so my question is like in the title : the different between Analog and Digital signal? 
 
I saw someone said that they has the coaxial or optical output/input so what is it used for? if you can please give me some example about the full system for me to easy imagine
 
Some speaker or amp are more expensive than the other because they have the optical/coaxial output? so why? and how can we use it ?
 
For me I have laptop/PC/Mp3 player so if I want to make some optical or coaxial or something else how can I do ( the only way I know is put my DAC/AMP to 3.5mm of laptop/pc and put my headphone/speaker to AMP by the attached cable)
 
Thanks 

 

[PurpleAngel]

Audio is stored and processed in a digital form, amplifiers and speakers and the human ears are analog.
So there needs to a DAC (Digital to Analog Converter) in the middle.