The weirdness of it all

It would be interesting to see exactly what these different cables do to the sound. This could be done with a before and after measurement of the speaker. People say you can't measure these differences, they're something that only the human ear can pick up, not any machine. I just don't believe it. I was told that about amplifiers too but when I perceived a different sound between two amps, I took measurements of the speaker using the same test signal into the amp and the difference showed up clearly as a change in frequency response from the speaker. Mystery solved! Anybody ever measured their speakers before and after a noticed difference in sound quality after a cable change? It would give more meaning to your subjective descriptions to get an objective measurement of the change. 

I think measuring the speaker's output is the correct thing to do because we're looking at the result of how the system is interacting with all of it's components, not just how one component operating by itself measures into a test load. 

Good cables beat lamp cords any day. Moving on up to fuses now, not as clear cut. Bottom line is I have gotten to a point where all I do now is listen to music because the obsessing part with the sound thing has magically gone away. I guess that's when you know your system has pretty much arrived. Great satisfying feeling. It took a crap load of time and effort to get to that point though. No pain, no gain is a true part of this audiophile pursuit.

The cable's effect not only differs for each kind of cable, but also its length & connectors, and the amp & speakers used.  I'll keep this simple, since even that is above my pay grade, and only consider resistance, although changes in inductance & capacitance are also in play.

From the amp pov, the cable adds to the resistance it's driving.  That usually results in a (slight!) reduction in the amp's output - but some circumstances could result in an increase.  From the speaker side, the cable resistance adds to the source impedance, lowering damping & resulting in the amp having less control of the speaker (this is why tube amps generally have looser bass than ss - they tend to have a higher output impedance).

Sorry, it's hard not to say "impedance" when talking about audio - that's the result of the complex interaction of inductance (L), capacitance (C), & resistance (R)  in the circuit and of course is frequency-dependent.  So what I said above is true, but additionally complicated by the cable's L & C, and different at every frequency.  The choice of amp & speakers also affects this interaction to varying degrees at every frequency.

Conclusion: If you like how your system sounds, good on you, mate!  If not, cabling can make a difference, but the results are not as measurable or predictable as upgrading your electronics.

The importance of power cables can't be overstated. There is no reason why they should be limited to audio equipment. I love the fact that my Samsung S95B OLED has an IEC power socket, so I can use a decent power cable. Like audio equipment, the improvement is fantastic. Just as audio equipment benefits from isolation feet, so does the TV. The IsoAcoustics ISO-Stage 1 Combo Isolation Board works well and more importantly supports the weight and is stable.

BTW, this isn't sarcasm, but something I wholeheartedly recommend if you want your visual experience to be top-notch.

@petaluman If the audible impacts of cables are due to LCR interactions, the math describing those changes is well known and not very difficult. And as a result, easy to document. But it's a double-edged sword, the inability to document such conditions removes them from consideration. Stereophile for one runs a frequency response of amps into a simulated speaker load with frightening results.