I am not an electrical engineer, but a mechanical engineer with a decent amount of experience with data acquisition and a lot of good BS sessions with other EE's. My unconfirmed [open for more experience] thoughts:

Burn in is indeed an electrical charge alignment of the atoms in the make-up of the cable, alternating currents can do that. I believe its biggest influence is in the capacitance and inductance realm, which is critical. Low end cross-overs (i.e. low or high pass filters) are routinely just RC or RLC circuits, so if the cable has a varying inductance or capacitance, it can effect signal attenuation. Those being my understanding of the facts, I can't even being to imagine how small the contribution could be in a system with such low voltages and short cable runs. In a system running at 20 volts, with milli-amp current over 100 meter runs, though, you can see quite significant aliasing of mid to high frequency data.

As far as the 'little copper wire inside the components go, I tend to be in agreement. It does seems strange. My only thought is that extremely short solid conductor may perform very well, whereas longer (1 meter) flexible multi-strand cables are much more fickle. Obviously shielding is paramount, but it also is fairly remedial. If it is shielded, it is good for just about anything. But I could see why someone would feel strange about connecting a set of $100 cables to a $90 component with little bare copper connections inside.

My personal experience has been that cables which are correctly shielded perform better than those 'half-way' cables on the $5.00 rack. I have never done a good blind test, but then again I don't own any really expensive cables. Speaker wire is critical without question. Coarse wire from home depot sounds completely different from fine wire by Monster. Again, its an inductance phenomena, I would suspect.

I do think, without reserve, that cables and speakerwire and all of the esoteric changes involved at that level are 'ultra-fine' tuning a system. Proper speaker placement, careful routing of wires and maybe a power conditioner would be my order of operations for a system tuning long before buying ultra expensive cables. But maybe I'm just limiting my system. Who knows? The debate started in the early days of audio and will continue as long as we don't have digital impulses piped directly to our brain. But its always interesting to hear another point.

Sandy.