I used to believe 100% that there is no way a power cord could affect sound quality - and then I went and did something I thought rather innocuous and found otherwise. Granted the pc in question is a very unusual one in that is is rather cheap and it uses ferrite cores, something usually only found on power cords used with digital computer video monitors and TVs. Anyway, the pc in play was one I found in the discount bin at HH Gregg and it was a 12 gauge cord that I thought might be of some benefit in handling all the power coming from the wall that feeds my entire system through a PS Audio Power Director 3.5 power conditioner/surge protector, which comes with a stock 14 gauge pc. There are 12 components fed by this single wall connector into the PD 3.5, including a plasma TV and two power amps, and it is common for as many as 8 devices to be on simultaneously. So I figured a 12 gauge pc would be better than 14 gauge in that particular connector. The power cord I bought was the AR (Acoustic Research) PR
903 and it is 12 feet long (longer than I need really). It cost $20, normally $40-50 I found out later when I went looking for a six foot version on line. So this is not a "high end" snake-oil type cable situation, although it is probably as well built as any of those megabuck power cords. But the unique thing about it is the ferrite cores on each end, which I have never seen before on a general use power cord.
So while I was concerned about because the excess cord that tended to form loops (not a good thing I know), I inserted the cord in my system and decided to do some listening. I really didn't expect to hear anything special, so I was shocked to realize that indeed something had changed noticeably in the sound of my system. Most noticeable was that I could hear backup singers and overlays much more distinctly than before, and lower frequencies had an energy that I did not notice before. Vibrations and harmonics from stringed instruments were enhanced to an amazing degree. There really just seemed to be more of everything, really. I swapped the AR pc and went back to the stock cord just to be sure I was not imagining it and the differences were very clear and audible to my ears.
There were other benefits as well - picture quality on my TV seemed to be cleaner and have less video noise, and that included video from my DVD player and DVD recorder. And 5.1 audio from certain ABC's prime time shows was greatly improved as before I often had trouble hearing dialogue over the background music ABC often overdoes. Now that was no longer an issue because apparently my JBL AV-1 processor just seemed to do it's job better after inserting this power cord.
I decided to see if another "upgrade" power cord would make a similar difference and I found a 12 gauge PS Audio pc on clearance for $40 (half price). But no - it sounded just like the 14 gauge stock cord. So I conclude that the AR PR
903 is a rule-breaker, and I can recommend it to anyone who can find one. But good luck with that because it appears that AR no longer markets this power cord. I searched the net looking for a six foot version and could not find a single vendor that carries this cord in any length. I did find a 14 gauge AR cord in a blue color that may or may not produce the same results.
So to the OP all I can say is if you can find this particular AR power cord then give it a try. Otherwise, if you just want to satisfy your curiousity without wasting any huge sums you might want to try the very nice looking Pangea power cords sold exclusively at Audio Advisor. They are surprisingly cheap and were apparently designed by a guy with good credentials. They should provide enhanced shielding against RF and EMI and appear to be as well made as any of the megabuck power cords. They start at $19 and go on up depending on gauge and length. They are the only other power cords I would consider but I really doubt if they will do what the AR power cord did for me.