i.e. here is some difference and I don't really know why.
Based on what data - subjective listening tests or measurements? I'm not sure I would trust either from a source with invested commercial interests regarding cables.
Like most hifi tweaks, there's simply a lack of hard data. The only vaguely scientific studies I have seen are blind listening tests with and without expensive power cords in which listeners failed to detect any SQ difference. While such studies suggest any differences are very small, they are far from perfect or conclusive.
With respect to power delivery, I�m surprised the likes of Paul McGowan haven�t analysed the output of a hifi unit�s PSU with and without upmarket power cords attached. I would love to see e.g. a comparison of a G68�s power supply performance (noise etc.) in such tests. If electrical interference reduction is the main benefit then the positioning of �normal� cables should be critical and moving them in close proximity to sensitive cables, kit etc should have an impact of SQ � again no studies that I�m aware of.
I remain open minded but sceptical in the light of what data are available.