M4A → AMR

Yes, and it is worth planning around. Both formats are lossy, so the AMR encoder is working from audio that has already been through one psychoacoustic pass, and its own decisions compound the first set. At 192 kbps or above the result is still transparent for most listening. If you have a lossless master anywhere, encoding the AMR from that instead avoids the double pass entirely. An M4A holds AAC in most cases, or Apple Lossless (ALAC) when it came from a lossless rip. AMR is a narrowband speech codec running between 4.75 and 12.2 kbps, modelling the human vocal tract rather than the full audio spectrum.

Not intact. M4A carries a proper metadata block, but AMR has no standard place for artist, album, track number or cover art, so tags are dropped rather than mangled. Keep the M4A as the tagged copy, or re-tag afterwards with a tool like Mp3tag or MusicBrainz Picard. AMR destroys music: its 8 kHz bandwidth removes everything above telephone frequencies, and no amount of re-encoding brings it back.

DRM. A subset of M4A files are encrypted by the store or the software that issued them, and encrypted audio cannot be decoded by any converter. Anything you ripped yourself, recorded, or bought without protection converts normally; a licensed purchase will not. M4A hides two very different things behind one extension — lossy AAC and lossless ALAC — and non-Apple hardware support is inconsistent.

Because one side of it is a speech codec rather than a music codec. It models the human vocal tract and discards everything outside telephone bandwidth, which is fine for a voice memo and destructive for anything with instruments in it. Converting away from it cannot restore the missing frequencies — they were never encoded in the first place.

If M4A is lossy and AMR is lossless (e.g. MP3 → WAV), the AMR is no better than the M4A — you cannot recover information already discarded. If M4A is lossless and AMR is lossy, the AMR codec recompresses; at 192 kbps the result is transparent for most content.

Several files in one job need a paid plan. Free use is one file per conversion, one conversion an hour. On a paid plan you can add several files to one job, then download each result on its own or all of them in one ZIP.

By default yes — 48 kHz M4A stays 48 kHz in AMR. If you need to downsample for compatibility (96 kHz → 44.1 kHz for CD burning), the sample-rate option applies high-quality resampling in the same encode pass.

Not in this step. The converter has no loudness setting and leaves the level as it is. To even out the volume, run the finished AMR through a Normalize tool on this site.

MP3 plays almost everywhere. AAC plays on Apple devices, most Android phones and Sonos. FLAC plays on Sonos and Android but not on older iPods, and WAV plays on nearly everything but makes large files. There are no device presets on this page, so choose the target format your player supports. AMR makes voice recordings absurdly small — an hour of speech fits in a few megabytes — and it is what many phones still record calls in.