@georgehifi , there’s more to it than that... generally speaking, SETs behave as power sources rather than voltage sources (which might be your typical solid state amp). The reason to go this route is to avoid the brightness and harshness often associated with loop negative feedback (harshness and brightness is after all a coloration and not one that is particularly pleasant).
Because no feedback is used, you can’t rely on the Voltage Paradigm for flat frequency response, and the 4 ohm tap may or may not help (likely won’t, as the speaker may be looking for +3db worth of power in the woofer section, and merely moving to the 4 ohm tap won’t get you that).
There are speakers that are designed to work with amps of higher output impedance (and no feedback): Merlins, Coincident, Audiokinesis, Quad 57 and Quad63, Classic Audio Loudspeakers, Rogers LS35A, Lowthers, PHY, Festerex, most horn speakers and many more.
Because no feedback is used, you can’t rely on the Voltage Paradigm for flat frequency response, and the 4 ohm tap may or may not help (likely won’t, as the speaker may be looking for +3db worth of power in the woofer section, and merely moving to the 4 ohm tap won’t get you that).
There are speakers that are designed to work with amps of higher output impedance (and no feedback): Merlins, Coincident, Audiokinesis, Quad 57 and Quad63, Classic Audio Loudspeakers, Rogers LS35A, Lowthers, PHY, Festerex, most horn speakers and many more.