How to tell the current from the amp

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.

So there is no one measurement available to indicate the “current” capability? I don’t have electrical technical back, and I feel this concept is being mystified…

@dragoncave

The problem you’re up against is marketing. Often solid state amps are advertised as having a certain amount of ’current’. That can be quite different from the current required to drive the speaker load properly when the amp is at full power. You might want to read the article at this link:

http://www.atma-sphere.com/en/resources-common-power-amplifier-myths.html

As an additional hint for good sound: avoid loudspeakers that are excessively low impedance (less than 4 Ohms) or low efficiency. The reason is that all amplifiers made more distortion driving lower impedances, and low efficiency loudspeakers (less than 87dB) tend to suffer thermal compression caused by heating in the voice coil. You might think that additional distortion is inaudible (that its 'negligible') but that isn’t the case. The ear interprets all forms of distortion as a tonality and it is keenly sensitive to the higher ordered harmonics since it uses them to sense how loud a sound is (and the ear has over 120dB range)- so more sensitive to those harmonics than anything else! So when your amp has to work hard for a living, the additional distortion it makes will be mostly the higher orders. This contributes to harshness and brightness (the tonality assigned by the ear) as well as a loss of detail, which affects things like sound stage depth and width, as well as nuances.

So the difference in distortion is not only audible its also measurable.

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.