100, 70, 25V, 16, 8, 4, 2-Ohm — it’s all the same physics, just different math. We are simply ensuring that the loading is appropriate for amplifiers, wiring, controls, and speakers. With power wiring there is a single frequency. With audio there is a range of frequencies and the loading varies with frequency. “Impedance” appreciates and reminds us of this variation. (Unfortunately, with some added math)

In some respects we could consider our 8-Ohm stuff as a 25V system.