perhaps traditional dynamic drivers would have been better. You looked at the right page though, the explanation is right about the paragraph you excised:
"It is a power trans-conductance amplifier (or power current source, if you like), replicating an input voltage into an output current. A regular amplifier sends output voltage to the loudspeaker. This is not that kind of amplifier.
This amplifier ignores the elements in series with the load circuit, including back-emf, wire resistance, inductance and such, and creates voice coil acceleration in direct proportion to the input signal."
Has anyone here heard (or considered the upgrades) the F1J?