in the case of the B&W 802 you need to have 3 db more power into the 4 ohm woofer load as you do into the mids and highs because the woofers are 3 db less efficient. I am ignoring the effects of feedback here and doubtless there are amps that don't quite double power that can do OK on this speaker.
Atmasphere, it still seems that you have confused the fact that the maximum clipping power of an amplifier is simply not any kind of indicator of its output impedance. And as you well know, as long as a given amplifier is below clipping, it is the output impedance, NOT the maximum clipping power, that determines how much a given (complete) loudspeaker's frequency response will vary simply as a result of its non-linear impedance characteristics.
Incidentally in a loudspeaker design, it is NOT the efficiency and impedance of the drivers that are the biggest factor in determining how much impedance variation there is across the spectrum. In fact, most older (i.e. 1960s) loudspeakers have far more than 3dB efficiency difference between the direct-radiating bass/mid-bass driver(s) and their horn mids and highs. And these are speakers that you would consider to have relatively flat impedance curves, and are very "OTL-friendly".
Rather, it is the relationship of the bass drivers to the cabinet, and the choices made in crossover design, that are the key factors in determining the impedance curve of a complete loudspeaker. Which also of course has nothing to do with Paradigms of Philosophy or Increasing Cheapness on the part of loudspeaker designers, and especially has nothing to do with the Rise of Negative Feedback . . .
It's true that loudspeaker designers over the past several decades have indeed moved toward designs that rely less on mechanical damping within the drivers themselves, and more in the combined behavior of loudspeaker cabinet. But this shift is attributable to the monumentally influential work of the Austrialian A. Neville Thiele in the 1960s, and the continuation/publishing of his work by Richard Small in the JAES in the 1970s - for which we have the equations and parameters that bear their two names. Also hugely important was the work of Edgar Villchur in acoustic-suspension loudspeakers and dome radiators, and the huge advances in materials science . . .
These and many other truly scientific efforts are what we have to thank for the amazingly high level of sound reproduction that we enjoy today . . . so you'll forgive me if I bristle at a crumudgeonly, dogmatic analysis that attempts to force it into those old unsolveable harps of "tubes-vs-transistors" and "feedback=bad".
