how does current work in an amplifier?

That is a perfect conclusion Magfan and Atma. Speakers and amps work as a pair. And I agree with Atma that speaker impedances dropped when SS became more common. High impedance, high efficiency speakers with a tube amp is probably the most cost effective quality sound/dollar. And here I am sitting at the opposite end of the spectrum with a massive amp, low impedance speakers. It sounds great, but I have to alert the power company whenever I plan to crank it up:)

Tony, except that tube amps tend to be more expensive and high effiency speakers tend to need help extending the bass, which doesn't come cheap either.

I've heard Maggies and tube amps work very well together.

The dealer did use a REL sub also though however.

I would strongly consider a tube amp were I to reacquire a pair of Maggies someday.

My caveat is tube amps and Maggies are both relatively finicky solutions in terms of what is needed to optimize results, so you have to be willing to deal with that.

A nice thing to do if you have Magnaplanars and tube amps is to back the amps up to the crossover and use a speaker cable that is as short as possible- 6 inches is a good length, and make the connections as tight as possible. This can have a profound effect on the bass impact!

Unsound is right, tube power is expensive relative to transistors. This has been the case since forever; in the old days when transistors were coming in, manufacturers realized that they could build a transistor amp for about 1/10th the cost of tubes, but were able to charge about 90% of the retail. There was a tremendous financial incentive!

Speaker manufacturers, seeing that SS amps could double power into 4 ohms, began producing 4 ohm speakers that had larger voice coil gaps (easier to make). This cut their driver cost by a similar factor, and again it was possible to charge nearly as much- another financial incentive! IOW, it was cost and the ability to make more money that drove the rise of transistors and low impedance speakers in the 60s and 70s.

Athmasphere, I have a question for you.

First, background: In this discussions most of participants when refer to impedance mean only its modulus.

from Simon Thacher of Spectron paper
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... loudspeaker loads comprise complex impedances with both resistive and reactive (capacitive and inductive) components. Such impedance can be depicted as a vector with its magnitude (modulus) and angle (phase), and both vary with frequency. In general, the voltage and current waveforms, in complex impedance load, are out of phase with each other and therefore, to characterize accurately a speaker's load impedance, both modulus vs frequency and phase vs frequency plots must be known. Frequently, the phase angle is much more crucial to the speaker load than the modulus alone

To deal with this phenomenon, Keith Howard ("How Much Power Do I Need?" Hi Fi News July-Sept, Nov 2007 ) introduced the figure of merit he has labeled Equivalent Peak Dissipation Resistance (EPDR). This is, simply, the resistive load that would give rise to the same peak power device dissipation as the speaker itself. Using EPDR as a figure of merit, the speakers can be compared directly with each other.

Sorry for tbe long introduction: Question is simple: do you agree with Keith Howard figure of merit (EPDR) and if so why speaker manufacturers are not utilizing it, and amplifier manufacturers are not demanding it?

Thank you.