I want increase the headphone output for my rooted nexus 7 4.4.4 kitkat Tablet

[AC Question]

I enjoy my nexus tablet a lot however whenever I take flights it is nearly impossible to hear my movies. I am looking to just simply increase the volume of my headphones. I have the volume turned up and still it is very hard to hear. I have tried to use various volume booster apps but most seem to be a hoax or do not work with Kitkat 4.4.4. Please even a little bit more volume makes a difference!!!