Help with math and science of tri-wiring?

All to the same taps.

Actually, this is a very interesting question! I have never thought of doing that. KR4, is there a reason why all the wires should be connected to the same tap? I mean, on my amp ... the 4, 8, and 16 Ohm taps are just slightly fewer coils on the output transformer ...

Perhaps my question was inelegantly phrased. I am hoping that someone knowledgeable about electrical engineering can tell me rules of thumb or actual scientific facts to help me better understand the results I achieve (and maybe achieve better results) connecting my loudspeakers to my amps. Specifically, I am optimizing performance by best matching current delivered to load impedance at different frequencies. Amfibius, it is interesting...although I don't think Kr4's our go-to guy on the subject.