[LAU] audio compression of all alsa output?

I've got a system I'm doing tech support on, and I'm trying to get all audio streams normalized/compressed before the audio is spit out the speakers. Basically, we've got several buttons that play an audio stream through mpg123. The streams are different volumes and that understandably upsets the customers when they change audio streams and it's suddenly blaring christian contemporary music at their patrons. Does anyone know of any way to do this, or at least any little compression/normalization apps I might be able to pipe the data through? I would prefer to avoid JACK, but that's only because I don't want to have to do more work than necessary, and this isn't (rather, shouldn't be) a very complex system. Any input would be appreciated. Thanks. -Nathan PS: This godawful thing is running on FC4 (vanilla, for all intents and purposes), btw.