What's an easy way to increase volume on custom music without it being too loud?

[Swoftu]

I've been trying to change some of the music but I usually have to boost the volume way up and this ruins quite a few songs as they sound terrible at that volume. When I downloaded the Epic Music Mod, some of the song had less volume than my converted tracks, but still sound fine. Is there any way to have a normal volume with these?

[zYnthetic]

The music in KF is pretty heavily compressed which is somewhat common for the style. Orchestral music is quite the opposite though. Peaks may be nomalized to 0db or close but compression is not often used or used very lightly. Further complicating things is this mod takes music from several sources, each produced w/ different mastering techniques.
So unless these other songs are remastered to match the compression levels used in the default music (which for the style may sound bad), they're all going to sound quiet in comparison.