Hi,

How sure are you you're hearing clipping and not harmonic distortion? How sure are you the song doesn't just sound like this when highlighting certain frequencies as you've done? I think if you want a more conclusive test you have to try generate some reference tones with a reliable source and feed them into the player. The tones should be generated at different volume levels (-20, -15, etc). If it's fed in the form of an MP3, I'd suggest encoding them at 320 kbps just to be safe. Otherwise WAV if you have spare space for it.

And then to monitor the output, I wouldn't use headphones or an amp, unless you're 100% sure the distortion isn't occuring there. I think pulling it in via the line in on your PC is a good idea. Better yet, if you have or know somewhere that you can borrow a scope and other test equip...


Regards,
Aragon