Click on the Playback tab, and switch on Lossless under Audio Quality. On a Mac running macOS 11.4 or above, you must click on Music > Preferences in the menu bar when running the Apple Music app. You can also listent to Lossless Audio through an Apple TV or Mac. How to turn on Apple Music Lossless Audio on an Apple TV or Mac They can often be reasonably pricey and you will need an additional Lightning to USB cable (A or C depending on the device). This is a device that sits between your iPhone and headphones that processes audio independently. You will need a dedicated third-party DAC for that. Unfortunately, you cannot listen to Apple's 24-bit 192kHz High-Resolution Lossless Audio through the Apple adapter. If so, plug them into the adapter and you should hear the benefits. You should also make sure that your headphones are capable of rendering 24-bit 44.1kHz or 48kHz - Lossless Audio, basically.