Most headphone lines with copper as raw material, the average purity (generally with a few N said that such 4N, 6N ......) the higher the conductivity, the better, the smaller the signal distortion, common are:

TPC (copper): purity of 99.5%
OFC (oxygen-free): purity of 99.995%
LC-OFC (oxygen-free copper linear crystalline or crystalline OFC): purity of 99.995%
OCC (single-crystal OFC): the highest purity of more than 99.996%, is divided into PC-OCC and UP-OCC
5, on the front-end equipment: Many HIFI enthusiasts accustomed to phono turntable and separated into two parts in order to get better sound quality *** is music.
Front: Multi-audio system refers to the signal source, such as profiling slow turn LP player or CD player, sometimes referred to as a tuner (tuner) in the process received a signal from the radio to the previous level.
CD turntable: the mechanical transmission part of the CD player out of the machine independent.

D / A Converter: Digital audio products (such as CD, DVD) in the digital audio signal into an analog audio signal device. D / A converter can be made independent of the machine to match the CD turntable, in which case is often referred *** (DAC).