Apple Music Streaming Quality
Apple Music can burn through your data connection, just like any streaming music service. Apple confirmed that the Apple Music streaming quality changes depending on your connection, which should help. Plus, you can download songs from Apple Music to your iPhone for offline playback.
When connected to WiFi the iPhone will play Apple Music at 256 kbps, that's in line with Amazon Prime music, but not as high as the 320kbps of Spotify, TIDAL and Google Play Music.
While connected to a 4G LTE connection the Apple Music service will drop down to 128 kbps according to one report. This translates to about 50MB of data for one hour of listening on LTE.