The Truth About Power Cords and there "Real" Price to Performance

I've heard a few power cord demonstrations and it is really easy to hear the difference between the hardware store IEC cords and even modestly priced specialized power cords.  I've only heard a few comparisons within a brand line between expensive and ultra expensive cords, and the only one where I was quite impressed with the ultra-expensive cord was a NBS demonstration involing their Black Label cords.  The Black Label sounded considerably more dynamic, and I liked that result in the particular system used for the demonstration, but, I have no idea if that particular effect comes with negative consequences in a different system (it is all about tuning/compatibility).

The most recent demonstration I heard was one done by the Isotek people.  They demonstrated a $400 cord against the hardware store cords, then, using their chord, they added in their various power conditioning boxes.  I ended up buying two Isotek conditioners which come with this cord, and upgraded the power cord feeding one conditioner with their more expensive power cord.  Decent power cords and conditioning make a substantial difference.

One of the most impressive demonstrations I've heard involved a comprehensive system for grounding equipment.  It is the system developed by Nordost.  The before and after sound employing the grounding scheme was quite impressive.  I was particularly surprised because I generally don't like Nordost interconnects and power cables.

I heard two blind power cord demonstrations, where the two cords were both of similar price, and it was fairly easy to distinguish the cords in both cases, but whether or not one was better might be system and taste specific.  In one of those bind auditions, I thought that a power cord by Basis Audio was clearly better (can't remember what it was competing with) because the sound was more dynamic and lively sounding.  But, when I tried the cable in my own system, it sounded a bit too hard and brittle. 

It is not necessarily a comparison between different price components; it is a matter of what sounds right.  It also matters what component is being powered; I've tried different cords on some components where I've really not heard a difference.  As a rough rule, tube gear, particularly linestages, seem to be somewhat insensitive to changes in the power cord.  I don't think it is necessarily a matter of how much power the component draws either; I've heard differences with DACs that cannot be drawing that much power.