They're lovely cables, Chris. However, the scope results are exactly what I would expect going from unscreeened to screened mains cable. I don't think there is strong evidence there of the connection between the amount of screening of the mains cables and improvement to the sound emerging through loudspeakers.
As noted by other respondents, the effects of screening the final 2m of mains cable could be:
- reducing the radiated emissions from the mains cable to the equipment
- reducing the received interference by the cable from external sources
The extra ferrites will reduce common-mode high-frequency effects being transmitted both to and from the equipment along the cable. Most professional equipment already has mains inlet filtering fitted for EMC reduction, but the amount of suppression is usually determined by EMC tests rather than by listening to the result.
The thicker conductors and higher-quality connectors will reduce the impedance of the power source and the ground connection as seen by the equipment.
It would be interesting to know which of these factors produces the most audible improvement. I remember being suprised by the difference in the dynamic range handling of an otherwise good-quality hi-fi amplifier simply by re-wiring the power supply section, including elimination the mains inlet connector and power switch and hardwiring a thick mains cable to the wall outlet.