Thanks for grabbing the pro version!
Currently there is no way to import or convert a .wav file to an animation curve, since that isn't something that GM supports (or ever would). That being said, using a .wav file as a waveform reference should be possible. I already have a free library that allows you to read .wav files, and another free library that helps you calculate the audio "peaks", which is just a normalized value of the audio at given positions. Using these two libraries, you could definitely load a .wav file, precalculate the waveform, and use that as a lookup table with a synth processor in the pro version.
Unfortunately I currently don't have the time to add this feature to SynthEngine, but that is the basic gist of how it could be done. If you already have a wave table synth handy (and your reference .wav file is not too complex) then you could also reference the wave form when making your own animation curve as a crude (and less effective) alternative.