I don't know what you mean by complex EQ analysis, But look into linear system theory and linear systems characterization. A loudspeaker is mostly, yes mostly described as a linear time invariant system. If you capture an impulse response using a log sweep (see Farina papers) then you can see the non-linear distortion is at such lower level than the linear part that it's essentially irrelevant. The nebula uses volterra kernels, which you can obtain from a log sweep (if you construct it right). I actually built one myself but didn't make much of a difference in the final output, i.e. the linear part completely dominates - makes sense, as when the non-linear response starts becoming significant, the loudspeaker is so far into the limits of its mechanical excursions that it really sounds unusable - not what you normally hear when playing through a guitar cabinet. So again, no the "technology" is not limited as far as emulating a guitar loudspeaker.I was of the impression that even a great IR was basically a complex EQ analysis of a speaker cab with frequencies being run through it. I totally accept the fact that I may be wrong, so please do educate me rather than just blow me off.