It's Simple

I guess that is a long-winded way of saying that the higher quality my system is, the more a simple thing like a cable improves things, or the opposite. For my system and ears, I have found that to be a consistent reality.

@yping 

such as IMD, etc

Distortions like TH, IM, TIM are active components faults.

There are numerous other cable properties: Proximity Effect, Skin Effect, Purity, Metal, Plating, Insulation Dielectric, Fatigue, etc. All these properties have an effect, but well below LRC.

For all intents and purposes, cable R can be ignored as it is a minor fraction of speaker R. Longer runs, say 25 feet or 30 feet, cable R can equal amplifier R, cutting Damping Factor in half. Additional length also increases L & C, which can cause stability problems.

Cables should be as short as reasonably possible, of the same length and as straight as possible [Bends increase L, but this is more theoretical than practical].

In general, the more current, the shorter the wire should be. Therefore, amps should be as close as possible to the speaker with long inter-connects from the low level electronics.

Got it backwards ieales!

Ieales, Let’s imagine 0.1 ohm (both ways) cable connected to 8 ohm speaker that has lowest impedance of 4 ohm. At 4 ohm we have divider of about 1/40 equal to -32dB while at 8 ohm we have 1/80= -38dB. Do you think that 6dB difference in audible area won’t make any difference?

You might be right that cable R can be ignored only for the purpose of damping factor, since there is always speaker’s own impedance in series with back EMF force (and 2/3 of it is resistive), but one can argue that capacitance and inductance are not that important either. Almarg pointed out that speaker, having inductive character most of the time, has very high impedance at high frequencies (where cable inductive reactance can go as high as 1 ohm) while capacitance plays very small role because of low output impedance. As for the skin effect, that you mentioned - it starts at about gauge 18 with copper at 20kHz. Our ears are not very sensitive to volume change but are very sensitive to frequency smear. When you change loudness by 1 dB nobody will be able to detect it but when you adjust treble by +1dB you can detect it easily. In order to provide low resistance without frequency smearing companies split wires into multiple strands. It won’t help much as long as the strands are in magnetic field of each other (skin effect exists). To improve it cable designers place conductors on hollow tube (or flat cable pattern) reducing magnetic field to one that comes only from neighboring wires.