The iMP-400 comes with quality iRiver wrap-around headphones, offering far superior quality to standard CD player headphones. The player offers eight preset equalization curves and one user-defined curve (choose from normal, pop, rock, jazz, dance, classic, metal, U-Bass, and user EQ). Auto EQ changes automatically according to ID3 tag information, and a battery indicator lets you know when you're low. The player also performs perfectly in the face of external shocks because of iRiver's unique anti-shock algorithm, iRiverShockFree. This feature maintains supreme control over the server, so it can accurately read data even in the face of extreme vibrations, letting you listen to continuous music.

An easy-to-read, four-line LCD shows every bit of information needed, and an FM tuner comes in handy when you're traveling by tracking the frequencies to maintain reception as you move. The iMP-400 uses 16 MB Flash memory to support the display of Chinese characters (traditional/simplified)--37 languages are supported. The player also recognizes discs in Packet Write format, which enables you to use CD-RW discs like PC hard disks, offering the ease of using discs and of saving and deleting songs. Finally, the player prevents its rechargeable batteries from overcharging, and a discharge function fully discharges batteries before recharging, thereby preventing the diminishing of rechargeable battery capacity.