In theory, theory and practice are the same. In practice, however... Yes, mathematically, you can get impulse response via Fourier transform. In practice, you'

In theory, theory and practice are the same. In practice, however... Yes, mathematically, you can get impulse response via Fourier transform. In practice, you're using a current to push a coil against a magnet into a spring. A real current, a real magnet, a real spring. You get all sorts of non-linear behaviors. On top of that, the spring (that is, the driver) retains impulse energy as mechanical energy, and then emits it back in a nonlinear way, by moving that coil in the magnetic field - turning a motor into a generator, producing seriously nonlinear signal back into the amplifier that produced the original signal, where it's picked up by the distortion-correcting negative feedback loop, and... Yeah, that's not a simple Fourier transform anymore. If you had enough data points, it could be modeled mathematically. We don't have all the data, and don't yet have a good way to measure all that stuff.