I was looking up Logic's Match EQ plugin, which is very interesting, it analyzes a sound with a spectrum analyzer, remembers it, and analyzes a second sound, and then creates a complex EQ curve to give the second sound the same spectrum as the first. Suppose this is a similar idea to how Fishman's pedals (http://www.fishman.com/aura/default.asp) that claim to make your piezo acoustic DI sound like it is being mic'd up?
http://www.soundonsound.com/sos/jun05/articles/logictech.htm (http://www.soundonsound.com/sos/jun05/articles/logictech.htm)
Check this project:
http://www.sidus.eng.br/vh/violaohibridoi.php