M4A is AAC in Apple's favorite outfit: the audio-only MP4 your iPhone speaks natively. It was born in 2003, popularized by Apple's iTunes Store, and its real weak spot is older Windows software and stubborn car stereos that expect a .mp3.
Whatever the recording, audio just wants to be heard: the trick is picking a shape that plays where you need it. Stands in for any audio format Flippy can read: MP3, WAV, FLAC, AAC and friends. That makes it the right destination when what you need is any sound file: music, voice memos, podcasts, session exports.