I have a standard wallpaper (from my Gallery) and I did play music at one point through Samsung's Music Player, but then I closed it in the task killer (Double press home button.) I can't work out what it is. I have disabled Google Play Music for the time being to see if it improves as that would regularly open up in the "Active Applications" menu. Any other suggestions you may have will be appreciated.
It's a pain because people talk of going the whole work day on 75% battery, mine is down 5% during the 25 minute drive to work...