Its file hasn't been sent to that device yet. In Decaud on your Mac, right-click the song (or album) and choose Send to iPhone, or import it on the phone from a USB-C or SD drive.
DST-compressed DFF (the SACD compression) is not supported. Uncompressed DFF and DSF play in every edition. On the Direct Mac edition they can leave the Mac natively as DSD over PCM to a capable DAC; the App Store editions play them through high-quality PCM conversion, labeled in the signal path.
DSD512 files import, analyze, and play in every edition. Native output (a Direct Mac edition capability) tops out at DSD256 because macOS delivers native DSD as DSD over PCM, and DSD512 needs a 1.4 MHz carrier no USB DAC exposes to CoreAudio. Decaud plays DSD512 decimated and says so in the signal path, rather than calling it native. The longer why.
That depends on the edition, and the signal path tells you either way. The Direct Mac edition can take the device exclusively and match its rate, and shows Bit-Perfect when nothing alters the stream. The Mac App Store and iPhone editions are sandboxed: they play shared mode at the device's current rate, and the signal path labels every stage rather than claiming otherwise. In every edition, anything that would alter the stream (EQ, crossfeed, ReplayGain, resampling) is labeled, and everything alters honestly or stays off.
Settings ▸ About names it: Direct Edition or App Store Edition. The difference is device control (exclusive access, native DSD over DoP), which the App Store sandbox does not allow. The full comparison: Which edition?
On your device, as a local database next to your own files. iCloud sync is optional and keeps the catalog (titles, tags, artwork thumbnails, play history) in your own iCloud account. Audio moves only when you ask: Import to iCloud and Send to iPhone copy the files you choose through your own iCloud Drive, and Add External Drive Folder plays files in place without copying anything. See Privacy & Local-First Principles.
Found a bug, have a feature idea, or a file that won't play? Include your device and the format if it's about playback (e.g. "MacBook Pro, DSD128 DSF over a TOPPING DX5 II").
