Uhm, help me out here. What's the point in connecting a C2N to a PC parallel port!? It'd be much easier to use any MP3 file directly on the PC / convert it into a TAP-file.
Or, if you want to "record" old commodore tapes to MP3, use any tape recorder with a line out and plug it into your soundcard.
Do you want to play an MP3 during an adapter in a C2N to load stuff via pc printer port into a C64 emulator!?