I have not seen anyone mention this but I do believe that the iPad Air 2 has a louder volume output via the headphone socket. I don't have numbers but I notice that not only are my headphones not usable when full volume is selected, the output via my DJ cable to the amplifier at the bar where I DJ does not have to be as high as it was compared with my iPad 4th Generation. Same library, same DJ software, restored settings from iCloud but considerably louder volume. Previous settings for the bar with iPad 4th generation were: iPad on full volume, volume check turned off, amplifier in the bar also on full volume. Settings for the bar with iPad Air 2: iPad on three quarters full volume, volume check turned off, amplifier in the bar almost on full volume, but not quite.