Lanman1978
Android Enthusiast
Get this app and experiment with the settings. It is the only app that I found where I could get decent sound out of my headphones. Actually you have to get it from xda and install it because the playstore will say its incompatible, but it works just fine with our phone.
https://play.google.com/store/apps/details?id=com.noozxoidelabs.eizo.rewirepro
https://play.google.com/store/apps/details?id=com.noozxoidelabs.eizo.rewirepro