Sheilded/Unsheilded Power Cords

It really depends on alot of factors..
There are alot of power cords that are not shielded...
If there is shielding in power cords, it is usually small amounts of wrapped aluminum/tin or braided tin...
I have found that in power cord construction, shielded vs unshielded may make a difference for longer runs but short runs, musically, the unshielded cords tend to sound better. The sheathing, whether pvc or rubber etc makes a difference... The internal dialectrics make a difference.. The coating on the conductors inside the cord make a difference... There are many flavors of cords... Being a small manufacturer.. I have developed a line of cords that use Ferrite core rfi blockers by TDK to eliminate any noise..so to speak... Shielded or un shielded, there wasnt much of a difference... For digital components.. one may want a smaller gauge, shielded cord or filtered cord..
For power amps, and high current applications.. one may want to try a larger gauge cord with better internal dialectrics and heavy duty connectors for maximum signal transfer... On the other hand, some environments and systems are just prone to bad power ... ie, rfi in the area emi in the lines, and bad synergy with the interconnects and cable tv wire... So there is no right or wrong...
Choose a cable that suits your needs, and follow your cable manufacturers recommendations...Different cords may and will work better in some situations than other...
Just my 2 cents.
Joe DiMonte
Custom Audio LLC

A shielded cord will always perform in superior fashion to an unshielded cord of otherwise identical design. If it does not, some simple yet almost always overlooked design criteria were not taken into account during the construction of said cord.

The lack of design integrity with the shielded cord would become more apparent when using devices that produce high current demands on the power cord / wall outlet i.e. power amps, etc... That is why many people have better luck using shielded cords on low current devices ( digital, line level sources, preamps, etc.. ) but run into problems using shielded designs on power amps. I don't know of any commercially designed power cords that take such criteria into account. Those that are smart and / or familiar with magnetic fields will understand what i am hinting at. Sean
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No technical reason to shield power cords or speaker cables. These are low-impedance output drivers, so crosstalk is not really a concern. The only advantage might be if you wnat to run power cords side-by-side with unshielded interconnects. Then the power cord may crosstalk to the interconnects. This is fairly easy to avoid with minimal spacing however. Shielding just adds unwanted capacitance.