How do I adjust audio balance of my Android phone headphones out? My earphones are unbalanced - one  is louder than the other, so I need to adjust the sound volume balance to get it right.
How can I do it on Android?
There is a possible quick solution, depending on the phone in consideration:
Go to Settings->Sound->Music Effects and depending on the phone, you may by default have an app that controls the music effects within which you should easily find your desired setting. 

But if your phone is rooted, a more reliable solution would be to install the music effects app/driver:     Viper (basically a 3rd party audio driver for android) which can be  turned on or off at will. 

The app, in addition to being able to fix an unbalanced stereo has a powerful and wide spectrum of amazing sound enhancement options which is a must have whether you have an unbalanced stereo or not!
In fact I can't enjoy music with it turned off anymore :( - - - - ;)