I always wonder if anybody using esoteric “high end” AC power line cords has paused to consider the household wiring on the other side of their own listening room wall. That wire is ordinary AWG 12 Romex if it's for a 20 ampere circuit breaker, or (more likely) AWG 14 Romex if it’s for a 15 ampere circuit breaker. And what about that other ~ 10 miles of power line cable that extends back to the local power distribution yard? Hey, can your AC power line purity really be improved by adding that last few feet of costly “audiophile grade” power cord?
The short answer is: Who cares? All of the alternating current pulses, however fine or fuzzy, are going to be converted into a smooth stream of direct current. And it's only the purified DC, not any spurious AC, that will operate the ensuing circuitry. A modern solid state linear DC power supply utilizes full wave rectification with heavy filtering. EMI/RFI bypass traps are provided at the supply input, to shunt any high frequency noise to ground. Active components are utilized to enhance DC stability. Zener diodes clamp voltage levels and chop ripple. Precise series regulator stages are implemented where there’s justifiable merit. The consequent output is scrubbed free of extraneous AC artifacts—it’s just plain/pure/flat/steady direct current. And that can be confirmed by viewing the DC waveform on a basic 50 MHz oscilloscope.
While every audio component has it’s own unique DC power supply, every supply normally draws AC fuel from the same tank, so it’s vital to provide a fuel tank big enough to power all engines; see paper headed “Assuring Adequate AC Power”.
AC power line cords serve as pipelines that route the required AC fuel to each DC engine. There’s no benefit served by making that pipe fatter than needed. Every DC engine has a basic design task, and it can’t utilize extra fuel. For AC power line cords, the “fuel” is alternating current, and the capacity is defined by the conductor gauge. The original circuit designer assigns a gauge (AWG) appropriate for the required consumption. If you have good reason to want a longer or shorter cord, or one with an angled female connector, just let the designer’s AWG be your guide. Increase the conductor diameter only if you have to extend the length of the power cord well beyond its original design length. With respect to insulation, the commercial heavy-duty standard for prime AC power line cordage is type SJT, with molded construction. It’s quite excellent.
Be aware that you can buy top quality molded SJT power line cords, AWG 14, 16, or 18, made to any length, at http://www.stayonline.com/molded-cord-configurator.aspx. The price for such custom cord will be low when compared to a “high end” cord, but it will be functionally equivalent, and it will be of the desired length, without excess slop.
Do utilize AC surge protection; it might help in the event of a power line aberration.
