First thing that comes to mind is making sure the line out gain matches the recorders input. Basically turn the volume down on the output- microphone signals are very weak, like 50 or 100 times weaker. Your recorder is amplifying that signal beyond what the circuit can handle and you're getting distortion.
If there is a Line In jack use that instead. It may be a switch that says Mic/Line. If you only have Mic level input, turn the output down on the music until it sounds good on playback, and your data should flow.