I hear the difference between a tube amp and a modeler. I just don't get this 'respond musically' thing.
Every amp I have played, whether tube, solid state or modeled all made music when connected to my guitar. I like to think that the music comes from me, and my hands - instead of some electronic device, whether it runs on vacuum tubes or IC chips....that's the point I am making. I just don't see how you need help from said device to try to make your stuff sound 'musical'.
Either it already is, when it comes out of your guitar, or it will never be...