I just recently purchased the Google Nexus 6P and have been having issues with the sound output for Spotify app on Android 6.0 Marshmallow. It is very quiet when the audio cable is plugged into external speakers or my car stereo. I tested the phone itself by playing music on Pandora and other music apps and have no issues, so I know it is specific to the Spotify app. Furthermore, I can sometimes here the music jump to normal volume for a split second when I change songs, so I know that the app is dialing back the volume. The part that makes this problem hard to deal with is that the bass level does not get changed, so all of my music is overpowered by bass that is too strong. Any troubleshooting ideas would be greatly appreciated, since my phone is the primary way I listen to my music.