Music Player Consuming 40% battery in 2 Hours?

iPhone 6 Plus, iOS 8.3

Background apps refresh reduced,

all other apps except music removed from background,

4g, wifi, bluetooth turned off,

auto brightness off,

2 hours of not touching the phone (with no out/incoming messages or calls),

location based services reduced to be used by Find My Phone, otherwise set to "while using app"

was only listening to mp3s from the default player while putting the phone in locked mode (screen off),

2 hours, battery dropped by nearly 40%.

prior to that, if I leave the phone on standby (not even listening to music), the battery consumption seems normal.

Is the music player consuming that much power? Can someone please advise?