I've done only minimal testing so far. My test samples have been the first 30 seconds or so of Holst's Mars, and of Sledgehammer.

Heh, good examples. I remember when a friend of mine bought "So" just for that song. He cranked that flute intro because it was so quiet, and nearly lost his hearing and his speakers when the trumpets and bass came in.

Also be sure to make sure it works for fade-ins. For example, U2's "Wire" off of Unforgettable Fire, or Peter Gabriel's "The Rhythm of the Heat" from Security. Two other great examples I can think of quiet intros followed by loud songs are by Rush: "Show Don't Tell" from Presto, and "Animate" from Counterparts. "Animate" is simply Neil's voice quietly counting off the tempo, followed by a max-volume drumbeat.

This sounds really cool. I'm really interested in hearing something like this in action. Coolest long-term real-world test would be as a WinAmp plug-in.

One question: Isn't there some Prior Art on this sort of thing that you could look at? I've heard of TV sets that implement something like this...

Tony Fabris
Empeg #144