Цитата из новости на сайте MP3Gain за 8 января 2005 года

Dave Lasker has added AAC support to mp3gain.exe. He wrote aacgain.exe specifically so it would work with the existing MP3GainGUI without too much trouble. To get it all to work, go download the latest MP3Gain (either "1.2.5 Stable" or "1.3.4 Beta"). Then download AACGain. Un-zip aacgain.exe, re-name it to "mp3gain.exe", and move it into the MP3Gain folder, copying over the existing mp3gain.exe. That's all you have to do. Now MP3Gain should handle AAC files (.m4a or .mp4).