(oppss i was writing a long long paragraff and Internet Explorer refresh the page...)
Hello!, good news, this works!

im testing the sound and i can hear more level of output with my senheiser studio headphones.
i can hear that the sound quality is the same, its diffcult to explain what is the problem of the s4, because one thing is the volume and other is the quality of the signal, I have been testing the sound and i can appreciate at all levels, that the sound have a distorsion, i think that not a distorsion of noise, is like the music sounds overcompressed. i tested with some interfaces of my record studio like Focusrite Scarlett 18i8 and the sound isnt the same, some frecuencies from 50 to 600 MHz are limited and compacted.
try it, if you listen one of your favorite songs carefully with your headphones, you can hear "mini increases and decreases of volume level" maybe it could be the amplifier of sound, and how is gestioned. this is why i say that is like overcompressed sound.
i came from a Galaxy S3, and the sound quality and output level (with all stock of Samsung) is bad, worse than the s4...
i installed Siyah Kernel with Stweks in the s3, and WOW, the sounds turn into amazing!, (im speaking about flat presets, not "eargasm" or other settings) the quality is like my Focusrite, like my mac book pro, and others....
i heve read that Siyah kernel includes Vodoo Sound, and this is the reason of why the quality and level is better. could be the way of conversion of the signal from digital to analog, without noise and a best gestión of the chip phisical output amplifier.
i Heard other s4 models and their have the same problem with the quality, but i saw that there is posible to install other kernels like Perseus ,wich allows the use of Stweks.
is there anyway to solve this problem?
with mods,with kernel?? :silly:
jaja
thanks you so much for your constant help.

:fingers-crossed: