Honestly, though, if you've got the volume turned up and there's no sound, at this point we should be looking at more basic stuff.

- Are you actually playing MP3s?
- Like Paul said, can you see the time index counter of the MP3 counting upwards indicating it's actually playing?
- Have you hooked the outputs of the player into an amplifier that accepts line-level signals? (The player is not amplified itself.)

If all of those are "yes", then I'd say yeah, it's time to start looking for hardware defects.