Support page

See About lossless audio in Apple Music - Apple Support, in particular:

What you need to know about lossless audio in Apple Music

• Streaming lossless audio using mobile data or a Wi-Fi network consumes significantly more data. And downloaded lossless audio files take up significantly more space on your device. Higher resolutions use more data than lower ones.
• AirPods, AirPods Pro, AirPods Max, AirPods (3rd generation) and Beats wireless headphones use Apple AAC Bluetooth Codec to ensure excellent audio quality. However, Bluetooth connections aren't lossless.
• To get a lossless version of music that you've already downloaded from Apple Music, just delete the music and re-download it from the Apple Music catalogue. (Right-click > remove download, right-click > download)

Note that the lossless versions that you can download contain DRM and are only valid while you have an active subscription to Apple Music. You don't get a permanent upgrade to your purchases.

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