These discussions always do seem to become polarised, it feels like people have already decided what they believe to be true and no further investigation is necessary (as an aside, I didn't believe in high-end mains cables until I tried one).

Two quick thoughts:

* An early comment in this thread was about the skin effect at mains frequency being insignificant, yet our devices don't draw power that way. They take gulps of power when they need it, which (esp. with an amp) will mean much higher frequencies.

* Improved filtering in the PSU would make sense, but how far should they go? Build a £20k amp with the ultimate in power smoothing rather than a £4k amp? Not likely to work commercially (and that's ignoring the various patents around these things). In any case, how would you put a Shunyata Denali inside a DSP speaker? What about all those who would prefer to use an Everest? What happens if the next big improvement arrives before the next DSP speaker?

I get the scepticism, but try a decent mains cable before deciding. Your wallet may never forgive you, though grin

Prolific music listener / Hi-Fi addict!