Can hardly hear any sound from my mpc1000

just bought a mpc1000 a blue and red version, but when i play a sound pressing the play button or pressing a pad, i can hardly hear what is playing, and when listening to the headphones i cannot hear a thing. Please help? the master level is at 0db, and the main volume is on full, but still i can hardly hear what is being played, most times i can hear nothing. Any help will be greatly appreciated