The MOD ACID Audio Engine combines the sound quality of different audio MOD in order to obtain a very superb sound quality and higher than normal. This MOD can be installed on any device with Android ICS or above but only if you have ROOT permissions. Only the devices having display from 720 p or higher can follow one of two procedures either, but just one and not both. The MOD was developed for Android by a developer for XDA and combines different audio mods to get a better sound quality.”]
Source: https://blooglog.blogspot.com/2013/02/acid-audio-engine-mod-to-improve-sound.html