Any time. Reminds me of x-ray school physics. They teach all these mathematical formulas that almost everyone memorizes and learns by rote. Even the teachers, most of whom don’t really understand they just have learned the jargon and formulas. I don’t know why people put so much emphasis on arcane math when they could just as easily be teaching in a way everyone can readily understand.
Like impedance between source and amp, preamp and amp, whatever. Electrically the same as with speakers, at least in the sense of technical definitions. In terms of real world results however, very different.
With speakers we want to get a lot of work done, to move a lot of air. Moving air takes power and since high impedance increases resistance to power flow it is harder to get that work done and this is why for example the Tekton Moab is 4 ohms even though it could easily be 8 (and is an option) but sounds better at 4. In spite of what many will say looking at it from a purely amplifier distortion point of view while ignoring the the fact we need that power to do the work of moving air. Their misunderstanding blocks them from getting good sound.
With amplifiers it is a different story. With amps the input signal doesn’t need to move air, it just needs to maintain low distortion. Different story, different use of impedance. With the amp we want a very high impedance, so that it does NOT require a lot of current with even the most dynamic highest levels to drive the amp. This is why we see amplifier input impedance in the tens of thousands of ohms. A really high input impedance makes it easier for the preamp to "drive" the amp with low distortion. We can get away with this here because we aren’t "driving" the amp in the same sense as we are driving the speaker.
Even so, you will notice when people try and go direct from source to amp they invariably find better sound quality adding a preamp in between. Why? Because even though the power needed to maintain the current needed to drive a preamp or amp is very low, it is not zero. Source components typically are made with very weak output stages. This is why virtually everyone who goes from running direct to using a preamp reports a nice improvement in dynamics, bass and slam. These are the things that call for more current. The preamp has the current to drive the amp a lot better than the source alone does.
I am deliberately oversimplifying in order to make this all easily understandable. Because I have learned over the years it is far better to understand imperfectly but USEFULLY than to memorize a lot of arcane jargon without really understanding much at all.
Glad you found that helpful. Hope you find this helpful as well.