The frequency response represents the bandwidth that the team responds in a linear fashion and should be greater or less than the human audible spectrum, ranging from 20Hz to 20,000. The S / N ratio represents the ratio of clean signal (music) in relation to background noise produced by the team: the higher this ratio the lower the noise. The harmonic distortion represents the level of harmonics introduced by the team, which distort the original input signal (music). The lower the THD the sound is more pure and means the team is of higher quality. Consider that the human ear harmonic distortion when listening to pure tones only sine waves with greater than 0.1% distortion. If it's music is impossible for the note due to the complexity and mix of the sounds involved.
For the first stage of the chain of sound, the signal, a CD of good quality and moderately priced on average exhibits the following characteristics: flat frequency response of 10Hz to 20kHz +0.5 dB, S / N ratio greater than 90 TDH dB and less than 0.05%. The difference between brands and models, usually lies in the quality of their circuits for digital to analog conversion and jitter level that indicates the precision of the clock that generates internal pulses digital device. These common characteristics, the average team, by far exceed the level of perception error of the human ear, so that the difference between a good player and a very good go unnoticed even for a demanding auditor.