To
see some fairly flat impedance curves take a look at my web page which
shows some of my designs impedance curves verses other name brand
models. Google any loudspeaker and see if they have a Stereophile
review and check out the curves of them. Unless they use series
crossovers, standard crossover impedance curves usually look like a
mountain range with large peaks and valleys. With a tube amp, this will
result in an uneven frequency response with bumps and suck-outs due to
the fact that tube amps will deliver more power to the frequencies with
the higher impedance peaks.
Disclaimer- I'm Fritz, the builder of FritzSpeakers
fritzspeakers.com/DreamWeaverFritzImpedancePage.asp