M4A to FLAC Converter — Free, Online, No Upload

M4A (AAC audio in an MPEG-4 container) is excellent for everyday listening on Apple devices, but it hits a wall with audiophile hardware. Many high-end DACs, network streamers (Naim, Bluesound, Cambridge Audio), and music servers like Roon and JRiver Media Center have limited codec support — they read FLAC and WAV natively but often won't touch M4A or AAC. If you've built a hi-fi listening setup around any of this hardware, your iTunes purchases and GarageBand exports simply won't play.

Converting M4A to FLAC moves those files into a format the hardware understands. FLAC is the lingua franca of audiophile audio playback. Roon, Audirvana, foobar2000, and essentially every hi-fi media server treats FLAC as its primary input format. The conversion also improves metadata reliability — FLAC's Vorbis comment tags are handled more consistently across audiophile software than M4A's MP4 metadata atoms.

It's important to be honest about what the conversion doesn't do: because M4A uses lossy AAC compression, the FLAC output will not be "true lossless" audio. The FLAC container stores the decoded AAC audio without any further degradation, but the quality ceiling is set by the original M4A encode. Converting M4A to FLAC gives you compatibility with lossless-only hardware, not a quality upgrade over the source file.

Typical sizes (3-minute song): M4A 3–6 MB → FLAC 20–40 MB.

FLAC will not restore detail the M4A encoder removed, and the file gets bigger.