Current source (very high source impedance) drive of dynamic drivers can reduce some harmonic distortion and eliminate thermal compression by bypassing the mechanisms that generate them.
Here is the Klippel large-signal model for a dynamic driver.
The "voltage" (v) that drives the mechanical-system model on the right, is the force-factor [Bl(x)] times the current in the electrical-system loop on the left (i). If you force the current on the left with a current source amp, then the voltages produced across the elements on the left (and their non-linearities) become irrelevant, the current in that loop is solely determined by the amp.
Supposedly the benefit of current drive is reduced mid-band distortion, especially for simple dynamic drivers that do not have copper or aluminium caps/sleeves/rings [ which is most or all of dynamic headphone drivers.]