Why do AC cords make so much difference?

The filtering aspects would suggest a shielded cable. I can easily hear differences with unshielded cords, so there must be other factors. If you are comparing to a cheesy 18 gauge OEM cord there is a real difference. Perhaps it is the lower inductance, dielectrics, and wire size factors in high-end cords that make them sound better.

Has anyone here measured the capacitance between primary and secondary of a toroid transformer as opposed to an EI core? You will find about ten times as much capacitance with the toroid compared to a twin bobbin EI core which allows a sneak path for all sorts of RF nasties....Some IBM folks presented a study a few years ago to the IEEE of noise on power lines in major metropolitan areas and found huge spikes at 5mhz and 50mhz rather than the 27Mhz citizen's band they were expecting....With the profusion of toroid transformers, most of them center tapped to save on diodes, the noise is put right back into the neutral through the ground.......The vehicle I use to deal with RF noise is high capacitance and low self-inductance.....

Bob: Would your post above be one reason, or perhaps the main one, why many cords sound their best with the ground disabled?

Hdm, I wouldn't know as have not had a ground in over twenty years....The ground in my house only extends as far as kitchen, baths and laundry....

The info that Mr Crump presented about iron core transformers vs toroidals is pretty well known to anyone that has ever measured various aspects of transformer performance. Bob and i are basically on the same page in this regard and on several other AC related "beliefs". As such, you now know several of the reasons why i have preached the superiority of "old school" Iron Core ( E-I ) transformers in the past. They are quieter ( blacker background ) due to increased AC filtration and they ( typically ) offer better dynamics / bass performance due to reduced core saturation. I don't know anyone that doesn't want equipment with a lower noise floor and increased dynamic range.

I mentioned something similar to what Bob brought up earlier today prior to seeing these comments. You can follow along on the thread entitled Best Cable Tweak Ever. I'm trying to find a source on the web to support some of the info that i posted and as soon as i can, i'll forward a link to it in that thread or cut and past the info that i find. Sean