One of the tricks that I have used when the audio keyframes don’t transform the layer sufficiently is create an “animation only soundtrack”. I can pump the levels really high, render to .aiff, import, convert to keyframes and pickwhip. I can even use JUST the lower (bass) frequencies by placing a lowpass, rendering an .aiff, importing it, converting, pickwhipping. This is handy for using kickdrum thumps to force something to scale.
I just have to be sure to mute that “animation only soundtrack” layer or render the movie without sound if my soundmix is done elsewhere.
I have Soundkeys now (and it r0xorz), so I haven’t done this in a while.