Any way to assess which codec is used on iOS? I have the highest suspicion that Spotify (which is encoded in OGG) is being recompressed to the bog standard SBC codec. I have MDR-1000x (AAC compatible) and Spotify sounds much, much, much better on my bottom-of-the-range Sony Xperia XA Android phone (in Apt-X) than on my iPhone when using Bluetooth (and an unspecified codec). However, Apple Music (native AAC encoding) sounds great on my iPhone with Bluetooth - it sounds as good as on Android using Apt-X .