Here is what he has to say

""There are three ways to operate the RM 40, so-called because of its 40 inch vertical ribbon mid/tweeter array. The first is full range, with a single amplifier as a source. The system presents a steady 4 Ohm load, resistive above 166Hz, with 90dB/1W sensitivity and enormous output and dynamic range. Second, more ambitious audiophiles can easily switch the system to the biamp/biwire configuration and run a separate bass amp through the speaker’s passive bass and mid/treble crossovers which, by the way, consist of all premium parts such as Axon polypropylene caps and hi-Q Erse 14 gauge laminated core inductors. The third option is biamping with the passive bass crossover removed, an outboard 24 dB/octave electronic crossover driving the separate bass amp, and a second amp running the ribbon panels through their builtin 6 and 12 dB filters""