Any audio format that compresses sound, like MP3 or AAC, doesn´t get 100% of the quality of the original, always losing some sound (even if it is the minimum). However, if you are one of those users who doesn´t want any quality loss in any MP3, then you need SX Fidelity Amplifier 1.2.16.8. It amplifies and increases the audio of those files until it gets the same quality as the original, repairing or restoring those portions of the file that were lost during compression, and you can return to listening to the music in all its splendour.