robert jaybird,
jpryor wasn't talking about "warming up" in the sense of making the sound warm, smooth and tubelike -- he was talking about the warm-up period that tubes go through when you turn them on.
and jpryor, the POD's idea isn't unique or revolutionary, it's really an old idea that's only recently, with the advance of inexpensive computing power and speed, become feasible at realistic price points. The idea is that basically you can model the result of any physical process to a great degree of accuracy using the laws of physics and a computer that can perform the enormous number of calculations required. If it's a real-time process it has to do all that calculating very fast, too. The first products available on the market that did this kind of thing were the Roland V-something (I forget), a monophonic physical modeling synthesizer, and soon after, their VG-88 with its COSM (composite object sound modeling, I think?) architecture.