Can an MP3 player as a sine wave generator?

[Resistanceisfutile]

This is my understanding of MP3 players, please correct me if I'm wrong:
-The MP3 player generates a specific electrical signal (depending on the song stored in its memory)
-This signal is (eventually) sent through to the female audio socket
-This electrical signal is carried along the wires of headphones (or loudspeaker)
-When this electrical signal reaches the speaker inside the headphones (or whatever else) the electromagnet inside the speaker generates the corresponding noise.

Does this mean (or even if I'm wrong, would this still work?) that I could use an MP3 player (with a track of a sine wave of desired frequency stored in memory) to generate an appropriate signal?
(If so, could I use this in the place of a crystal oscillator, or would it only act as the piezoelectric crystal?)

 

[dick_freebird]

The player has its own crystal reference, no doubt.

The maximum frequency for a useful sine wave will depend
on the MP3 bit rate, I have seen nothing greater than 320K.
And there is likely some post-filtering at the output which
will keep things limited to the audio band.

But yes, you could (say) make a sine WAV file, convert to
MP3 and get a fairly pure looking low frequency sine wave.

 

[Audioguru]

An MP3 player is made to play clear music with low distortion so if it plays a recorded sinewave its output should be as pure as its input for audio frequencies.

 

[mrinalmani]

Yes it can. I have tried it with two different "Sony" players. The maximum voltage amplitude at full volume was 0.5V for both players. The output was taken from the head-phone jack.