OK, I just used my utility knife to trim the surranding area of the earphone jack. Now this player can take any headphones. The plastic is pretty soft, and easy to cut, as well as your finger.
Also, to those who still want to use this player, encode mp3 as 22050Hz, 48K bitrate. So this player can have usable length of music. Do not listen it using earphone, or connect it to home audio system at any bitrate. Use it in a car that has poor, basic factory audio system, and has noisy engine. Then, it will work fine.