The speaker needs an amplifier that can do a good job of making constant power with respect to its impedance. The reason for this is that the impedance curve is based on a capacitance, and so is decreasing as frequency increases. At the same time the impedance is quite high in the bass region, and many amplifiers will have difficulty making power at these frequencies as a result.
So. much like the 57, but with greater power handling ability, the speaker has always been a good combination with OTLs, going back to its initial introduction. OTLs are one of the few amplifiers that can make power in the bass region of the speaker, without sacrificing the highs. Its been my experience that the speaker can manage 100 watts alright, and it seemed a lot more fun with the extra power.