get 3rd party keyboard 

Download the latest version 5 (suggest to use aroma version) which are not buggy and use cwm to flash it.  During flashing make sure you select those related to S3 (Samsung).

Once you have successfully installed, there is an apps name "noozxoidelabs", launch it to configure the "Line-Out Audio Monitor".

Go to system settings>sound>music effect>, you will see Music Fx, Noozxoidelabs, and probably DSP Manager.  Select Noozxoidelabs.

This mod works very well with Poweramp and Playerpro.  I am using Playerpro though I also have Poweramp as I find Playerpro blend very well with the iem I owned.

If I am not mistaken, if you use Poweramp you have to un-tick DAC in the option.

If you are not using Siyah kernel, play with the equalizer settings in the Poweramp/Playpro.

For my case I set the equalizer in Playerpro to flat and only played with the internal hardware equalizer using apps STweak which allows me to do so as I am using Siyah kernel.

One has to recognize that you can only hear and enjoy the good sounding if you are using a very good headphone/iem.  Those average iem might not be so effective.

Sorry not DAC, should be DVC

Go to settings>audio>advanced tweaks>direct volume control

I can't recalled if I am not mistaken you need to uncheck for it to work.

You have to try out to see as I am using Playerpro now.

anyone try wnanamlite V4.4 ?