How to tell the current from the amp

As an additional hint for good sound: avoid loudspeakers that are excessively low impedance (less than 4 Ohms) or low efficiency. 

Agreed!!

A lot of people love the sound of the apogee scintilla, which is both low impedance and low efficiency.

Thank you all for the comprehensive science lesson. Really learned a lot here. I guess my point is the "lineality" (not sure if the right word) of co-relation between volts and impedance can be measured, and should be clearly marketed when a consumer is looking for a "current capable" amplifier, rather than using indirect formula to figure it out by themselves. 100/8 and 200/4 is just an indirect measurement, and i am sure there are ones perform 100/8 and 180/4, or more, or less. Why not just use one measurement to tell clearly, instead of leaving the consumer scratching the head and guestimate the math himself.

The education system’s lack of science is also reflected in a lack of critical thinking skills, that make the populous more prone to conspiracy theories.

Then add in marketing and prose, and it is like a shark feeding frenzy for a salesman.

I’ve mentioned the speaker’s impedance curve a few times.
If you were serious about making it easy, then I would have suspected you to have posted that? Or at least the name of the speakers in question.

You mentioned:

And if “current” is so important, why this is not a more easily marketable measure on the box of the product?

Are any speaker’s marketed as requiring specific amounts of current?

The reason why current is not easily marked on the specs, is that it is not really important except in some odd corner cases.

Current is not important.
- If the amp makes its voltage, then it also makes the needed current.