BTR AMP
FLAC (Free Lossless Audio Codec) is the most widely used lossless audio format: an open standard that compresses music to roughly half its original size with zero loss in quality. It is the default format for CD rips, Bandcamp purchases, and hi-res download stores.
Why iPhone can't play FLAC natively
Apple has its own lossless format, ALAC, and the built-in Music app supports that instead of FLAC. The Files app can preview a FLAC file one at a time, but there is no library, no playlists, and no queue. So playing a FLAC collection on iPhone means either converting everything to ALAC or installing a FLAC player app. The FLAC guide walks through both options step by step — for most collections, a player app is the simpler path because your files stay exactly as they are.
How BTR AMP plays FLAC
BTR AMP plays FLAC natively at full quality, up to 96kHz/24-bit and beyond — no conversion, no second copy of your library. Every track shows its exact codec details, e.g. FLAC 2933kbps · 96kHz · 24-bit, so you can verify what is actually playing. Files above 48kHz play at full resolution through an external USB DAC; on the iPhone's own output, iOS resamples as it does for every app.
Tags and cover art are read from the files themselves, and the on-device metadata editor handles Vorbis tags — the tag system FLAC uses — so you can fix metadata without a round trip to your computer. FLAC sits in one library alongside ALAC, AIFF, DSD, and every other supported format, with custom tabs and smart playlists built to stay fast at 50,000+ tracks.
Getting your FLAC files onto your iPhone
Your FLAC files transfer without iTunes.
Send files over Wi-Fi from any browser on your computer (Connect → Wi-Fi Transfer), pull them from Google Drive, OneDrive, iCloud Drive, an SMB share, or WebDAV, use AirDrop, or play straight from a USB drive. The transfer guide walks through each method, and the importing guide covers the details.