If I had to guess, they probably have a fairly accurate single-string model and then model energy coupling across strings. Another neat thing it does is it lets

If I had to guess, they probably have a fairly accurate single-string model and then model energy coupling across strings. Another neat thing it does is it lets you position virtual microphones around the piano (and open and close the lid), so they definitely have full-instrument spatial awareness in their modeling. One curious thing I noticed from the (simpler) string modeling synth in my keyboard is that if you up the dispersion it starts sounding like a bell... and indeed Pianoteq also has a very nice tubular bells patch. Explains what that's doing in a piano synth :)