It's a borderline case; a 2n7000 won't turn on entirely if you put 3.3V on its gate. Usually this is not a problem; its drain to source resistance drops sufficiently to act as a switch that is 'on'. But not all circuits may be happy with it.
However, I think it's more likely a connection/implementation problem; perhaps you swapped some pins or forgot to connect that common GND between the Arduino and the MP3 player.