I'm experiencing these problem that whenever I'm listening to music the volume drops automatically after a second of playing music to an average level despite selected maximal volume. This is independent of the tracks I'm listening to. Also it isn't dependent of 3.tmm Jack, Bluetooth or speaker. I am using Spotify premium since yesterday again since a few months now. It's a Nexus 6p on latest Android(6.0.1). It's also independent of volume normalisation on or off. Also disabling equalizers of other apps won't help.
Can this be fixed? Google and this forum didn't help me further so far.