Попробуй прогу Free m4a to MP3 Converter 6.0:
Руский интерфейс есть.
Функции:
AAC to MP3 converter.
Convert M4a to MP3.
Audio books M4b to MP3 converter.
MP4 audio converter.
3GP audio converter.
AAC, M4a, M4b player.
MP3 quality settings up to 320 Kbit/s, 48 KHz.
Drag&Drop.
Batch processing of multiple M4a, AAC, M4b, MP4 etc. files.
User-friendly multilingual interface.
Meta information (ID3 tags) is copied from source files. Converted files contain all necessary data: title, artist, album (if the data was present in the source files).
AAC to WAV converter.
M4a to WAV converter.