Because CD is copied from the master tape (the first version of the audio track recorded by the singer in the recording studio without any compression), it can retain the sound quality information of audio to the maximum extent. Music without loss of sound quality does not need such a complicated pressing process, so the sound quality is average.
to talk about the sound quality of an audio system, it is mainly to measure whether the above three aspects of the sound have reached a certain level, that is, whether the pitch has a certain intensity relative to a certain frequency or frequency band, and whether the amplitude of each frequency point is uniform, balanced and full, whether the frequency response curve is straight, and whether the pitch of the sound is accurate, which not only faithfully presents the original features of the sound source frequency or components, but also meets the requirements for frequency distortion and phase shift.