I am on DN3 RC2 and flashed S5 mod its a good rom , and i like to increased sound(as i were using boost sound in all previous roms i flashed). So did good research from XDA. After all decided to find ultra volume. And i noticed high volume after using this gain file. Just replace defaul_gain.conf using root explore.
Steps to use the mod are simple-
Download the attached default_gain.rar file.
Extract and find file default_gain.conf
using a root explorer replace default_gain.conf in the system>etc folder.
Backup your original default_gain.conf file in sd card location in case you want to revert back.
ENJOY Ultra volume (tested on dn3v5 its working )