Passive bi-amping works ?

Martin Logan's cross-over (not sure which speakers you have) with passive bi-amping allows each (hi / lo) connections to only draw power in that bandwidth. While active bi-amping usually yields superior sonic results, this passive bi-amping is very effective and less expensive than having to also buy an active cross-over. You do get significant benefits of passive bi-amping in this configuration over higher powered amps with bi-wire. The reason is the electrostatic panels can go to relatively low impedance. Depending on the music there may at the same time be a large bass spike (kick drum or something equally demanding). This asks for a large amount of power to the woofer, while the impedance is very low. This is an extremely difficult demand to the amplifier. By bi-amping (passive) these two demands are separated, so one amp can be handling the electrostatic (low impedance) demands and the other can be handling the bass (high power/impact).

1953 makes a good point which may have not been clear in my first post. The input to the amp is the full bandwidth (as 1953 correctly stated), but the load is only the hi/low that it is going to, so the demands on the amplifier as I stated in my first post are limited by the passive crossover. It will, as 1953 mentioned, make a substantial improvement.