WAV-PRG is a program for converting Commodore 64 tapes to PC and back. It is designed not to require any custom-built cables: transfers between PC and tape are done by means of a tape player/recorder connected to the PC's soundcard by a plain audio cable
I just did a "soft" test: I converted a .t64 to a .wav, converted it to MP3, messed a little bit around with it (add silence, make the quality a bit worse). At the end I converted it back to WAV, and finally .t64. Guess what? WinVICE could open it :D I LOVE YOU!