To put it simply, the impedance and frequency of various headphones are different, and the output frequencies of many playback devices are also different. As a result, many playback devices cannot exert the full effect of headphones. A very common phenomenon is that The volume of the same earphones on different devices will be louder and lower, and the sound of some devices is very low when turned on to the top. This will cause many of the performance capabilities of the earphones to be unable to be displayed, which will greatly reduce listening to music. Currently, if you listen to music on a mobile phone, of course it is SONY. The built-in WALKMAN has the best effect. I have always listened to music exclusively on the WALKMAN. I have used the Samsung I9100 and the effect is average. Nowadays, SONY mobile phones come with the built-in WALKMAN. The music effect is much higher than that of ordinary MP3 players. It costs about 1,000 yuan. There is no pressure on the headphones, but if the headphones are too good, you will need higher-end audio equipment to achieve perfect results! Such as lossless music, MD player, etc.