Why do designers/manufacturers...?

We use an IEC connector for the simple reason that no matter what cord we put on the amp, the likelihood is high that it will be discarded anyway in favor of the audiophile's preference.

We do however make sure we have the best resistors and capacitors in the actual circuit, or at least have them optionally available. I have seen too many times where someone thought they could improve the amp or preamp, only to turn it into a rat's nest in the process. Believe it or not, neat wiring often sounds better since stray capacitance is better controlled!

Atma-sphere,

Maybe you could correct my understanding, but I thought most power in the US is at 60Hz? Which high frequencies are you referring on a potential power cord?

What most people don't understand is that the first thing an the power from the wall does when it hits your amp is go through a transformer to cut down the voltage and then hit the rectifier which is converts it to DC. Yes the cap converts that rectified signal to a smooth DC line. I have used some very fast scopes and never seen the DC on that line changing. Most listening at home is well under 30watts so the power through the cord is relatively low. Even if there is fluctuation in that DC voltage, on a SS design is dropped again by a regulator to the rail which gives the whole system margin for any voltage regulation.

The only way one should here an issue caused by the power supply (including the cord) is if the DC voltage fluctuated and unless you have the volume turned up to 11, it doesn't.

I have been to some very big name audio manufacturers and as far as tweaks at audio shows, they use them because the parts are given to them to use, but at the home office, they use cheapo cables and power cords. Either these large companies are just cheap, deaf, or don't believe in tweaks, I don't know, but I am guessing it's the last one. Engineers love numbers and most tweaks can't be proven by numbers.
For cables that rob a system of 40% of their power, that means there the equivalent of a 40 ohm resistor on the cable. Whoever made that cable should be fined and put out of business.

Scvan, sure. How a power supply works is you have the transformer, rectifiers and filter caps. When the amp is running, it discharges the filter caps slightly between each peak of the AC power waveform. The rectifiers only conduct when the filter cap voltage is lower than that of the power transformer. What this means is that current will only flow at the peak of the incoming AC waveform.

That current spike can have some pretty steep risetimes, in order to charge the filter cap properly. A steep risetime corresponds to a high frequency. If the power cord limits the risetime at that frequency, the power supply will not charge up properly.

You can see this in an amplifier by running it at power and then substituting power cords. You can often see a difference in the power supply voltage, even though at the input of the amp the line voltage is unchanged. This is why some power cords can have an audible effect- and its also measurable. Anytime you can hear it and measure it you can also regard it as real.

Now this says nothing about the cost of the cord. It does not have to be expensive; it simply has to work.

why is it " illegal to use solid core wire in an AC power cord"? Is there a fire/heat hazard? Does that mean only that a pc must have multiple strands of wire? What exactly is "solid core wire?" Isn't all wire "solid" in a sense?

I have always wondered about all that stuff - wall socket, plug, wire, another plug, amp input socket - between the romex in the wall and the amp. Is there no way around the fire code?

Romex is solid core. If you flex it enough, it will break.

A legal power cord will be multi-stranded which means it can flex without breaking.