Can the built-in Music Player record from the built-in Mic?
No. The Music Player demands that the audio cable be connected, for good reason too, it is a Line In Recorder. If you wish to record from the Mic, you must use the Recorder program to record in AMR format (limited to 1 min per clip; use Extended Recorder (records in AMR/WAV) for unlimited). However, you should be able to connect a mic using the converter and record from it using the Music Player.