Math + Logic + Science = something completely mad...

Jitter for one is bidirectional. It causes harmonic distortion and uncorrelated noise.

  I'm not sure what "bidirectional" means.  Do you mean "sidebands"? 

Jitter does not cause harmonic distortion and that's the reason why is still audible in spite of very low levels.   Jitter only produces additional frequencies NOT harmonically related to root frequency.

Yes, it is causing noise, but it can be correlated, uncorrelated or both.  Uncorrelated jitter is a little less audible.  Correlated jitter is less audible when sidebands are closer to root frequency (frequency causing jitter is low).

It appears that according to numbers nothing in cables should be audible.  Skin effect, that starts at gauge 18 causes extremely small impedance change at 20kHz - frequency that I cannot even hear and where most speakers (being inductive) have high impedance.  Capacitance plays very little role in speaker cables and the same goes for dielectric absorption.  Inductive reactance, assuming both wire gauge and wire spacing of twisted pair to be 50mils, would be in order of 0.1ohm at 20kHz and 0.05ohm at 10kHz (that I can hear).
So, according to numbers, nothing should matter and all speaker cables should sound the same.  The problem is that they don't. 
Perhaps audio, like women, is meant to be loved, not to be understood?

dletch2, I remember long time ago I had inexpensive cable from Best Buy. I believe it was Monster Cable brand. It consisted of two parallel runs of very thick stranded wire in thick clear plastic (most likely PVC) insulation. It was suppressing high frequencies to a such degree that I had to add few dB of the treble on my receiver. Later I replaced this cable with AQ Indigo and magically treble came back (everything else being the same). Indigo was OK, but Acoustic Zen Satori that replaced it is in different league. What surprised me the most was lower midrange (cello, chestiness of male voices) that got fuller. In comparison Indigo sounded thin. I would not even try to express it in electrical terms. Since then everything else changed in my system for the better, but speaker cable is still the same. My hearing was not that good because of age, but I could still hear a difference between AQ King Cobra and Acoustic Zen Absolute interconnect that replaced it (foam Teflon, oversized tubes, Zero Crystal silver). It is cleaner, faster, darker background, more instrument separation. Why? Is it because of insanely good specs (6mohm/ft, 6pF/ft, 20nH/ft)? Calculations would likely suggest that both interconnects should sound exactly the same, but they don’t.

AudioQuest FAQ explains logic behind helical twist on oversized air tube. They stated that in order to avoid skin effect wires have to split into separate insulated strands, but then skin effect still applies since they are in magnetic field of each other. Remedy for that is to place them on the tube. That way each wire is only in magnetic field on neighboring strands. In addition it is interleaved with return wires to reduce inductance and twisted to reduce electrical pickup. That is exactly how my Acoustic Zen Satori is made. Different companies and the same design? Are they all doing it for show? Is it snake oil? I have pretty good understanding of electronics, but getting much deeper into something requires different expertise. I believe that we don’t even comprehend exactly the nature of electrical current. We know that it is motion of electric charge, but how energy can be delivered to load if exactly the same amount of electrical charge comes back by return wire? Why energy flows toward load while AC electric charge flows back and forth? Energy has to flow differently and it does - by magnetic filed outside of the wires (Poynting Field). Do we now understand everything? I remember some horrible amplifiers in 70s that had extremely low THD and IMD (achieved by deep negative feedback) and sounded bright and tiring. Later Transient Intermodulation (TIM) distortions were discovered. That makes me believe that trusting my own ears and cable companies is perhaps better than trying to make sense of it. I selected Acoustic Zen instead of AQ because it is better bang for the buck, IMHO.