Why Expensive power Cables when Romex behind Wall?

Could somebody please help me to shed light on this?
Is there any reason I should invest in expensive power cables when there's low grade cable between my outlet and the wall? I've upgraded most other components in my systems, but I'm just not sure that spending several hundred dollars for power cables makes sense, when the cable running from my outlet to the wall costs less than $.10 per foot. Can anyone shed light on this?

Boros: You have just put your finger squarely on the issue that many audiophiles with expensive power cables really don't want to admit: why invest a lot of money in a power cable when the electricity coming from the wall has just travelled hundreds miles, maybe even a thousand, through commercial power transmission facilities, been through umpteen transformers, and then traversed home wiring on the other side of the wall plug that is, at best, barely adequate? Unless you upgrade your home wiring with a high quality dedicated line, "gilding" the last 3-6 feet of the wiring with a $250 (or more) power cord doesn't make a hell of a lot of sense, does it? About the only rationale for doing this is to get a power cord with shielding/RFI filters to minimize RF interference, assuming you have such a problem.
This is an old subject. Just try a high grade power cord, borrow one from a friend or dealer. If you can hear the difference, great, if not, fine. I heard, and hear a major difference, major. There are many on the gon' that can give you theory about this. I simply tried it and was blown away.
I agree with Sdcampbell wholeheartedly.
I believe Sdcampbell is correct. At least to a good extent. I had a demo'ed a few power cords and owned a Cardas Reference power cord which came with my amp and is/was a decent middle of the road.

I ended up demo'ing and then buying three (one for each component) used Foundation Research in line power conditioners, LC-1's and an LC-2. These in-line power conditioners replace the power cord and IMO do far more to lower the noise floor, enhance 3D soundstaging, and sibilants and cost about the same as some good power cords.

That would be my recommended route.
BECAUSE there is a low grade cable behind your outlet and because it works. You don't question why a water filter works after your tap water travels 100 miles through some nasty pipe, it is similar with good power cords although not exactly analagous. Some people think that the power cord is the same as adding a few feet of pipe to an existing pipe, but such a pipe simply would not impede water flow, whereas a power cord can improve signal flow, filter grunge, lower distortion due to better grade materials. Just try one under $200 that can be easily resold if you don't like it. One audition beats a hundred debates in the posts. SD I respectfully disagree based upon personal experience, having been skeptical myself.
The logic of some above would make the use of fuel filters in
the car you drive.....well, stupid....ie: the gas you get is
so dirty..why try to clean it.

Or...the fruits, etc., you buy travel so many miles...why
wash them before you eat them?

Listen up guys........saying the cables you use in the last
link of the chain doesn't matter is like saying that the
signal broadcast by your local FM station is all there is..and that there is no difference in tuners......

Any link in a chain can be improved...and part of the high-
end is the fine tuning... This is what high-end wines, cars
and many other "things" in life are all about, that last
% of performance....without this pursuit by some very, very
good people..we could all be loving the sound of our 8-track
No offence Boros as I was once a power cord skeptic myself-- but I get the impression that you haven't actually auditioned any PCs yourself.

Audiogon should have a regulation that no one can ask this question unless they have auditioned at least five decent power cords in their own system, IMO of course. I auditioned seven in a week and it cost me nothing but shipping. Do a search and read the interminable comments. Cheers. Craig
The same could be said anytime you're trying to purify "garbage" : poor recordings, poor source, bad room. I, too, used to be a skeptic. I was espically skeptical of all cables and even most CD players. most recording travel down a $16 XLR microphone cable somewhere during the recording process. Since that is the weak link, why should I bother using a better cable than that? (rhetorical)

Auditioning interconnects a couple years ago opened my mind to that. And recently contructing several DIY power cables have opened my mind that sometimes, a power cable can make a SMALL difference. Even with the junk in the walls.

Try some. You won't hear differences in all systems. This is like the last 0.00001% tweak of your system. But in some systems you will. Maybe yours isn't tuned that well. Or perhaps your ears aren't? Or perhaps you have the wrong power cord? Generally, if you can't heara difference - you have some other gross inadequacy in you system - that may or may not be due to the romex in the walls.

I would fathom of the increased (or reduced losses ;-) ) of better power_cords/outlets/iec_sockets tend to be a result of the improved grabbing ability of the connections in making a solid connection. "Hospital Grade" stuff in known for that. That's why we use stuff like that. Better connections.

And you're right. After power cords. You'll start playing with power condititioners. Then you'll start replacing outlets (might as well, <$10). Next you'll run a dedicated line, one each, for - analog, amplifers, digital gear. Heheheh.
I was skeptical too... had some "pretty good" power cords that were made for me by a local cable deigner; better than stock cords but certainly not current state of the art. I had heard them compared to stock cords and could CLEARLY hear an improvement. That was 7 or 8 years ago. I have upgraded components since then, and got the system settled down... then began to audition new power cords. Some were no better, some were worse (even expensive ones). The ones that I settled on were again, clearly better in my system. It doesn't make scientific sense to me, but it happens. I tried making a bunch of PCs. I used romex all the way to the component; hard and hashy sounding. I tried a few different kinds of braided wire too; conclusion, this guy cannot make a PC that sounds as good as what the Power Cord magicians are making. Go figure? MG
This is an excellent question but that 6 foot high-end power cord can make an audible improvement. This similar to using high-end speaker cables. Most internal speaker wiring is tin-plated copper yet one can hear an improvement. There are many claims of how power cords achieve this sonic improvement by filtering, shielding, and lower inductance. Of course there are many so called high-end cords that make no improvement at all (IMO) so be careful in your selection.
"Hospital" grade sais it all. Would you feel safe, if the high tech respirator keeping you alive had a lamp cord and was plugged into a $5 power strip from Walmart? Hospital gear comes with big fat cords and plugs (plus conditioning) because they don't dare skip a beat (no pun intended).

Your gear won't skip a musical beat either.

Even though the cord is short, it still contributes to the overall inductance. ROMEX has up to 10 times the inductance of good after market power cords. If the the last 6 feet of a 20 foot run to the panel is an after-market cord, it will add very little to the inductance of the first 14 feet.
I always thought hospital grade just meant that it was designed not to produce any arcing when a plug is placed into the receptacle because of flammable gases that could be present in a hospital room?
Systems reproduce upstream content using upstream power sources (except some battery powered phono pre-amps). In that regard we spend ridiculous amounts of money. But our systems are (hopefully) designed to do the best job possible with the presented content and power source. So we spend our money to minimize changing, or losing, the content and to doing the best it can using the power available. But I'm in the camp which says that with my upmarket equipment the equipment designers have designed their equipment based on the known vagries of the power source (one of the design decisions requires overspec-ed transformers for example). So what the hell. Let the equipment do the job it's designed to do.

Having said that I've upgraded my PCs ! Just in case. If nothing else I get a better connection to the romex. Sad really.
Guys, if installing a supposedly high-quality power cord is actually producing audible differences in your system, then the power cord is not just passing the power without further distortion -- it's changing something. If your electric power supply is so bad that it needs to be filtered, then a power cord is NOT the way to achieve that objective -- you need a power regeneration system, such as those made by Richard Gray, PS Audio, Monster, etc. After you get the regenerator, THEN go for the good quality power cord.

(For the record, I also have high-quality power cords installed on most of my gear. These cords are probably the only "tweak" I've acquired that provided very little -- if any -- improvement in my system.)
It's true that some components are designed to be invariant of the power-line voltage. Some Linn equipment is like this, particularly when switching power supplies are used. However, in most amps, the linear power supply is not even regulated, and the capacitor bank is not infinite and the inductance from the cap bank to the output transistors is not zero, so they are sensitive to the line voltage, particualrly during high-current high-frequency transients.
Sdcampbell... Now that you are accustomed to your system's sound; ALL AT ONCE without listening; replace all of your cords with the typical black 18awg cords that come with most gear and computers. Then play your favorite most listened to recording. Does it really sound the same?? If you replaced the cords over a long period one at a time, you may not have noticed any change, since it was gradual.
Sdcampbell, being an Audiogon member that has always read your posts during the last two years ( I began in 1999), I am surprised by your comments.

You built your system with quality audiophile gear and yet you report that power cords provide very little if any improvement in your system.

This completely baffles me, as my results are so opposite from yours. You may have read about the extremes I have gone to make my electrical system the best it can be. Including but not limited to: Private transformer, 220 Volt three phase electrical drop, 750 Amp commercial bypass meter box, 16 dedicated runs exclusive to the stereo, separation of phase between digital and analog, and dedicated 12 gauge copper star grounding for each component.

With all this work, I cannot imagine music without a high quality power cord. I choose Purist Dominus power cords for my system, and the effect is so drastic, that an entire room of people laugh out loud when a stock cord is substituted. The difference is literally that big.

Do I remember you live outside of the USA? Maybe that is part of our different results.
I heard a rumor that the infamous Robert Lee @ Acoustic Zen is coming out with an inwall a/c powercable made of his Zero Crystal Copper to address this specific issue. I can't wait to try out some of that stuff.
Ok, here is my current thought train on this; Yes, I agree that I would not want to be "hooked up" in a hospital with lamp cord and a $1.49 plug. Fortunately for me, none of my gear came with such low grade pcs. I truly doubt that when Nelson Pass sits down to design military grade circuit boards for my equipment, that he is going to cut corners on the pc. I don't think top notch designers put cheap pcs on $3k+ amps or preamps, why would they? Sure, mid-fi and lower does not go to extremes, but then you are not paying the arm and a leg in the price for those extremes. So where do I think money would be well spent as far as power goes? Drop a dedicated line from your breaker box to your gear. Get a quality 20 amp breaker (hospital rated) and use hospital rated romex, carefully run the line without staples or cable nailers to your location, and then use a hospital grade outlet(s). I really can't imagine anything better than this other than buying a power rectifying device (PS audio, Threshold), which would nullify the need to do this providing it has the capacity to meet the demand placed on it. If you buy a power supply that is not big enough for the demand, you have gained nothing. The dedicated outlet is a LOT less expensive, but would not provide all the benifits that a well designed power plant would provide. In MHO, I would keep the pc's that came with good equipment, and do one or the other properly depending on your budget. If they want to use the pc off my Threshold gear on me at the hospital, I have no problem with that. Tom
Hi Meby,
You are mostly correct, as that is one of the concerns providing it is being plugged into a hospital grade outlet, that it will not arc. If you do not plug it into a well designed outlet, it still could. The other design approach is to limit the possibility of a short because wires can not come in contact with each other unless the cable is completely torn from the plug, and by then it wouldn't be live anyway (providing it was wired properly). Hospital grade really means nothing more than very well designed. Tom
If one thinks it makes an improvement to the sonics, of his system, then why not? If you have a $1000-$3000 to invest, to improve a $100,000 system, then it makes good sense. Where it doesn't make sense, in when that $300-$800, is spent on a PC, when it would make a much greater improvement, being spent elsewhere, in a $3500-$7000 system ie; room acoustics, dedicated lines, etc.
Fletchj, I could not agree more.
I also agree Fletchj for a small system; but will add that simply replacing those OEM 18 AWG cords with similar 14 AWG ones ($6 each), or the Belden Voltex shielded cables ($12 to $15 each) will still have a noticeable change for a few pennies.
I agree that relatively nominal amounts of hifi budget may be far better spent on room treatments than on the "upper level" (in price)powercords. I think part of the reason this doesn't always happen is that it is very easy to buy a PC and swap it out with the stock cord. What isn't easy is figuring out what room treatments to do, in what combination, and with what materials to address specific sonic problems.

That being said, I think there IS benefit in going with a "decent" upgrade to the power cord, but no real benefit in going hog wild on, say, a $500+ PC, unless of course you have more money than sense and don't mind lining a few pockets other than your own. I have Harmonic Tech and Ensemble PC's and they did improve the sonics of my system over the stock wire. However, I tried several more expensive cords recently (which shall remain nameless in THIS thread) and could not tell much, if any, difference.
I once read an article about using home electrical wires for networking all the computers/control devices in a home togeather. The article went into all the well known sources for noise on the power lines and how the carrier waves were tuned to the higher frequencies to avoid all the garbage. It could be that the high dollar cables are simply acting as high pass filters for the electric signal. Different cable sound then being the result of different filtering, much like a parametric eq for power but with each cord having its own eq shape.
OK, guys. I can stifle my comments about some of the arguments presented here but this "hospital grade" stuff is over the top. How many of you really know what "hospital grade" means?

Simply put, "hospital grade" refers to:
(1) Current carrying capacity--not required to be excessive, just consistent with the power demands of the device to which it is connected. I.e. a "hospital grade" outlet on a 20 amp circuit must be capable of carrying 20 amps at a 100% duty cycle without overheating.
(2) Strain relief--sufficient to assure that if the plug is jerked from the outlet by pulling on the cord the wires will not detach from the plug and create a shock hazard.
(3) Freedom from leakage--microshock is a major concern when dealing with pacemakers (for example) thus leakage must be very, very low.
(4) Adequate grounding capacity--which many audiophiles then turn around and defeat.
(5) Assurance of power transfer from outlet to plug--accomplished by wide plug blades and outlet contacts with sufficient spring loading to assure that the contacts make tight contact with the blades. No gold, no silver, just good honest brass.

Nothing, repeat NOTHING about the "hospital grade" designation bespeaks any kind of rfi or emf protection, filtering capability, exotic capacitance or inductance characteristics, "oxygen free" copper, special conductor configurations, rocket-science dielectrics, or other esoteric properties claimed for high end power cords. The sole concerns are safety, reliability, abuse tolerance, and durability.

"Hospital grade" in audiophile circles is primarily a marketing mantra. Just wanted to clear the air a bit.

will (with 30+ years in healthcare)

Underwriters Laboratories Standards UL 2601-1, UL 1778, UL 1363, UL 1449
National Fire Protection Association Life Safety Code 101
Hospital Grade a marketing mantra? NOT! If you tried to market any cable for any purpose by calling the parts Hopital Grade when they are not, you could be sued at the very least, and maybe arrested for fraud; because Hospital Grade is an industry standard that means something.

You could sell the cheapest, most poorly made audio cable on the planet; and call it "Audiophile Grade"; because there is no industry standard that I know of.
That's a marketing mantra.

So if you buy a cable with Hospital Grade parts, there is no guarantee your system will sound better, but you can at least be sure you are getting a good quality cable for your money. There is no guarantee an Audiophile Grade cable will have good EMF or RFI protection, or make your system sound better either. The only difference is the Audiophile Grade has the potential to be a piece of junk.

Those $60 Absolute power cords are audiophile grade solely based on the reports that the audio equipment using them sounds good. They are massed produced by a cable company in Taiwan that can produce 6 million cables per month. They claim hopital grade in their ads, but looking at them I wonder?? (a Taiwan Hospital, not USA?)

With respect, Sugarbrie, your observation is (1) not correct and (2) not directed to the point I was making. There is no legal or regulatory definition of the term "hospital grade." The way that one COULD get into difficulty would be to advertise that a cord met the various UL or NFPA standards that I mentioned when, in fact, it did not. I suppose it is remotely conceivable that one could face a suit for false or misleading advertising based on the common usage of the term but for someone to bring such a suit against an audiophile vendor would be hugely improbable. De minimus non curat lex.

But that wasn't my point. My point is that the term "hospital grade" implies nothing of audiophile interest other than heavy wire and good quality terminations. It has nothing to do with the esoteric properties often claimed for audiophile power cords.

I'm NOT talking down high-end power cords; don't get your knickers in a twist about that. I'm just informing people of what "hospital grade" means. And, perhaps more importantly from a sonic perspective, what it does not mean.

As to the Taiwan cords, ignore their use of the term "hospital grade" and see if, in the small print, they assert that the cords meet the UL and NFPA standards. That's what really counts.

Right/Exactly: The Absolute cords are probably UL and NFPA rated for a piece of audio equipment (so is lamp cord), not hospital equipment. They are giving the impression they are better than they are by putting in terms like Hospital Grade and then adding the fine print later. I have nothing against those cords since people find they work. I have no direct opinion on them, because I have yet to try one.

I am on your side actually Will; and I may even be more skeptical than you. I am skeptical to any or all marketing claims. I am a big believer in people trying things for themselves and forming their own opinion. I guess if everyone did that, there would be a reduced need for salespersons. (Less ads actually sounds good.)

The original post mentions Romex in the wall assuming it to be poor. I assume there are different grades of Romex???
Happy listening.

Different wire guages, certainly, and different types of insulation so that some must be run in conduit, other run in open, etc. depending on local codes.

We're absolutely in agreement on this point: Buy what you can hear.

It's interesting that no one seems to disagree with what I said earlier in this thread, and no one is saying that expensive pc's are a good investment. That must tell you something. Tom
There's something that Bill Parish (GTT Audio/Absolute Power Cord) taught me: "The last eight feet (of power line) are the most important."

A year later I have a very clear idea on this subject--and also why cryogenics is the most cost effective treatment. It's in the very last feet that the electric particles/waveform gets shaped prior to entering the audio component. As such, there will be a profound influence on sonics. Tice TPT, cryogenics, Bybee filters--they all work on some aspect(s) of reorganizing the particles/waveform prior to entering the audio component.

This has been THE most important lesson I've learned since coming back to the hobby after a five to six year break.
Trich727, you must have somehow completely overlooked my post.

Would you please provide references/documentation for this statement: "It's in the very last feet that the electric particles/waveform gets shaped prior to entering the audio component."

Don't hear more than I'm saying. I'm not challenging the statement, I just want to know its scientific basis, as opposed to the opinion of the individual that makes and sells the cords.

Many thanks,

"It's in the very last feet that the electric particles/waveform gets shaped prior to entering the audio component. As such, there will be a profound influence on sonics."

This is nonsense and technically incorrect. Just because some saleman says does not make it true. The network created by the conductors from the transformer and then from the panel to the outlet and then from outlet to the component all contributes. You can easily perform a SPICE simulation on this simple model.

There is nothing magical about the last 6-10 feet of wire unless perhaps it has a transmission-line termination in the plug or on the cord. An added network of this sort COULD prevent/reduce high-frequency reflections or resonance on the overall wired network. Whether transmission-line effects occur and if so, whether they would affect the delivery of power is debatable and difficult to prove.

1) I'm hearing it.
2) I thoroughly read Bybee's website and non-mathematical explanation.
3) This is also congruent with George Tice's viewpoints.

I have no electrical background, but I had a Materials Science Engineering roommate in college. Everything they do is related to crystal structure. Cryogenics deals with ordering (reducing the entropy) of the crystal structure. Electrons behave both as particles and as waves. Noise floor in the conductor lowers as a result of rearranging the particles in space--that's a no brainer to me. There's a lot we don't know for sure...

A few weeks ago I was studying for a pre-employment chemistry test and while reading about orbitals and crystal structure it all clicked in place.

What are the basic scientific activities?

1) Observation (hearing, smelling, etc)
2) Search for regularities
3) Investigating the why
4) Communicating findings

Will, just send one of your power cords that you have two of for cryo and do your own experiment. Other people have been doing it and posting their results in other forums.

Now that Sean has a ONEAC noise reading device we'll be able to conduct some experiments on noise control tactics and get numerical data.

Until then, don't knock it 'till you try it...
Hi Albert. You are correct, I did not read your entire post. I got to where you were explaining the lengths you had gone to improve your service, and stopped there. Now that I have read the entire post, I have a couple of questions for you. Is your private transformer a pole or slab transformer? Can you tell me the manufacturer and model number of the unit. The reason I ask is that I was a custom home builder, built a home for a Doctor who had about a $150k system a few years back. This guy was driving me nuts trying to get me to change his transformer because he was having to spend thousands of dollars on hi end power cords, and he blamed the transformer (also private, but because of his location). I spent an entire evening at his home listening very carefully to his system, while he switched power cords to prove his point. And he was right, the expensive power cords did make the system sound better. But his argument was that he did not previously need them. Finally I called in a favor with a friend at FL Power, and had a new transformer installed for the Doc. It was by a different manufacturer. Not even a day passed and the Doc was on the phone to me inviting me for dinner and thanking me over and over. He wanted to prove to me that he was not nuts, so I accepted. We went through the identical listening tests as with the other transformer, switching pc's, but this time - NO DIFFERENCE could be distinguished between the expensive pc's and the stock Levinson pc's. And I have to say that his system just sounded better over all. There was one pc that did seem to sound different out of the 10 or more we listened to, but I can't honestly say it was better. At the end of the evening, the Doc gave me a $500.00 tip and told me I had "saved his system". So, if you have a room full of people that all hear when you switch pc's, I would say that it is very possible that you have a bad transformer. I don't mean defective, as FL Power tested his old transformer, found nothing wrong with it and installed it on another street. Jerry, my friend at FL P did tell me confidentially that the difference between the two transformers was aluminum. One used some, the other did not. So, if you can tell me the brand and model of yours, I will drive up to the Doc's home (he no longer lives there, but I can still check the transformer). And it just so happens that the very next home I built has the same type of transformer (I had become keen to noticing this by now) as the one I replaced on the Doc's home, so I can check it too. I doubt there are that many manufacturers of transformers commonly used by power companies, so I've got a feeling you may not have even heard your system at it's best yet.
Trich, I have absolutely no doubt that your comments are true. My years of listening and testing have shown me that the only absolute is "we don't really know anything."

I have no idea about the transformer, it is a 25K VA model supplied by TU Electric, and is the third one on my home in the last few years.

Between the wet tree limbs, squirrels and Texas weather, this neighborhood is hell on transformers. That being said, the last two sounded identical as far as I could tell.
Florida is not to kind weatherwise either, sounds just like yours. Maybe FL Power had to change his transformer too and it drove him out? Who knows? The guy drove me nuts for 6 months, but anything I know about hospital grade wiring, I know from him. He even went in and red chalked the slab with notes to the drywallers where he wanted the drywall glued and not screwed. He drove my electricians crazy too, but they made a mint off of him. He was paying the installers all kinds of money for "electrical favors". At first I was charging him when I saw things I wasn't making a markup on, but there came a point I gave up as my electricians charged me only the bid amount. Just one question though, being as that you went to such extremes to make your supply the best it could be; wouldn't a power plant of ample size been a better move? So that no matter what transformer you ended up with, voltage drops, spikes, etc, the power was cleaned and constant?
Psychicanimal - Just because a cord makes a difference does not mean that the last 6 feet is somehow magical. It still has to do with the inductance of the entire run to the panel. The last 6 feet reduces the overall resistance and inductance compared to a typical "rubber" cord. Cryoed cables can perform well because they are lower resistance.

I make cords myself and you can see all of the measurements, analysis and theory on my website:
I may be naive and this may garner some 'flames' but ... I've got to believe that the main impact of upgrading a PC is not to do with the cable but more the CONNECTION. Hello ? There are two of them. One to wall recepticle, and one to the equipment, if I understand correctly. My guess is that if you simply unplug and replug an existing PC you'll end up with a better connection and hence, hopefully, improved sound. Cleaning these connections would help to.

Freezing them (I'm in Tahoe) - does this help ? Bummer that it only gets down to -20c here in winter and the better half would be distinctly uphappy if I opened the windows and shut down the stove to improve the sound ;-)
No flames--I read a post in the Asylum by Jon Risch where he says he suspects 50% of the sound in power cords is due to proper grip...
For fun, do a little experiment, buy an inexpensive steel or brass outlet cover and install it in place of your plastic outlet covers. Plug in your system and listen.

You should notice a big change in sound.


I will spit this out for discussion.

We cannot cure world hunger & explain every improvement we hear in audio as a direct result of decreasing capacitance and inductance while ensuring a low dielectric absorption. While this is important and the common angle to view how cables effect a system it is but a small piece of the puzzle.

Since everything resonates at certain frequencies, the wire (yes, the stuff inside our walls interconnects, and power cables) will resonate too. This is called (drum roll please...) Mechanical resonance. Mechanical resonance is particularly evident when energy is applied to something. Bang that drum again.... did you hear something?

While inductance and capacitance are very important in cable design and lets not forget dielectric.... Mechanical resonance is to a great degree what we hear when we hear differences in cables (and components). With power applied to the cable, it will resonate and thus emphasize certain frequencies, audibly changing the tonal quality you hear.

Cable geometry, and material used are key in producing neato sounding cables since they can effect the frequencies which resonate and those that don't. Different conductors will all resonate differently. For example: Copper resonates at 26.530MHz, Gold at 1.729MHz, Silver at 4.046MHz, and Platinum at 21.499MHz

The effects of the resonance of the material depends on the gauge of the wire and of course whether or not it is in contact with a sound deadening substance like Teflon - rubber - Shunyata Sand ... Virtual Dynamics Iron Powder or whatever. These substrates weight down the resonance to create the sonic signature.

Make sense?

Okay how about saying it like this:

Power coming into your house is already resonating - when you plug your cool aftermarket power cord into the wall, how do you think this could effect the sound? If the cable changes the existing mechanical resonance, it will change the way your system sounds.

So when you change your electrical outlet cover to a brass or steel cover and plug in your hefty power cord, you will hear a new mechanical resonance in your system and better understand as the topic of this thread reads -- WHY EXPENSIVE CABLES WHEN ROMEX BEHIND WALL... :)
Outlet quality and contact resistance is at least as important as the inductance of the power cord itself. Silver-plated brass outlets can work wonders for dynamics and detail.

Back to the question of the last 6 feet. Here are some calculations that I did to demonstrate the effect of a good 6-foot power cord:

A typical 6-foot 14 AWG rubber cord and 25 feet of ROMEX has inductance of 7.2 uH and resistance of 235 mohms, ignoring the plug resistance effect. Therefore, the voltage drop at 20kHz will be I*(wL+R)= I*(.905+.235) = I*(1.14). With a 6-foot Magnum2 and 25 feet of ROMEX, the inductance is 5.9 uH and the total resistance is 147 mohms. This is an 18% reduction in inductance and a 37% reduction in resistance. The voltage drop for this combination will be I(wL+R) = I(.741+.147) = I(.888). So at a fixed dynamic current I, the voltage drop in the entire power feed at 20kHz is 22% smaller with a Magnum2 power cord. I would consider 22% to be significant. The reality is even more compelling. When you add in lower plug and receptacle resistance and the fact that the di/dt on the power cord will have spectra well above 20kHz with some amplifiers, the low-inductance cord makes an even bigger difference.
Bwhite wrote:
"Make sense?"

Not to me. In fact, IMO mechanical resonances account for very little that is audible in most systems. Certainly if you put your components on a thin steel shelving unit, you might get some mechanical resonance effects, but most systems do not experience this. If anything, the electrical resonance of longer cables has a more pronounced effect. You are taking the snake-oil literature out there too seriously. Here are some papers that are not snake-oil:
Technical Papers and Audio FAQ at:
OK I’m an electrical engineer who has never tried to play with power cords. This means I know just enough to be dangerous but not enough to really know what I’m talking about. I am not going to claim that power cords do not make a difference because I suspect they do. That said, here’s my 2 cents.

Electrical power cord as filter: I’m not convinced but… The parallel is a fuel or water filter. Water travels for miles in dirty pipes but the filter at the end is able to clean it up. This argument does not work with power cords. A power cord is the last section of pipe, not a filter at the end. As such the analogy would be miles of dirty pipe with a clean section at the end. Not adding dirt for the last few feet isn’t going to help. A power conditioner is a good analogy to the water filter. IF the power cord has some form of filtering built in, that would be different. A power cord might include a high frequency filter to clean RF noise or something. Even if the designer didn’t intend it, the geometry of the wire could make a filter of some sort (I wouldn’t put money on it). Basically, I don’t by the filter part unless some form of RF filter was deliberately added.

Electrical power cord as the last few feet of pipe: Using the water analogy
1. The original pipe was too small (ie wire gauge too small). If the power cord was too small to handle the current you could get voltage drops. My 240wpc Bryston amp came with a heavier power cord than my Bryston preamp. Thanks to V=IR loading on the power lines and cord the amp might see a significant reduction in line voltage. I would expect this to hurt amplifier performance. If your system is plugged into a power strip this voltage drop might be shared with the other components in your system.
2. The pipe has flashing around the fittings (ie the plugs don’t mate well). Maybe the issue isn’t the last few feet but the connections at the plug. Just like the issue with small gauge wire, a bad connection can cause a voltage drop. This would explain why high quality hospital plugs can make a difference.
3. The last few feet of pipe is where all the dirt is! Perhaps the power from the wall isn’t that dirty but all your equipment is really making the noise. Shielding the cables as they near this big rack of electronics may make all the difference. Perhaps the worst dirt is the dirt generated by your own system feeding back into itself. This could explain why shielding may help.

Take it for what it’s worth. Personally I think cables make some difference but I would rather spend the big money on components rather than cables.
Audioengr. I knew you would reply! That's why I mentioned the steel or brass outlet cover. Its a sure fire way to prove mechanical resonance. Come on man, go get yourself a steel or brass outlet cover - they are cheap 2 or 3 bucks. Replace the cover you currently use with it and then let us know what you hear. Before you write this off as snake-oil you ought to experience what other people are hearing.

Here are quotes from Audioengr's "Technical Papers" - seems he is contradicting himself in claiming that resonance is for the most part not audible - and discounting it as snake-oil here on Audiogon.

Resonance is a very real behavior in most speaker cables. The nature of the speaker load will vary both the amplitude and frequency of the resonance. The fundamental resonant frequency is primarily a function of the cable length, but
different loads can move this frequency. Resonances can become a problem if high-bandwidth amplifiers are driving high-impedance speaker loads.

Empirical Audio takes resonance seriously, so we design anti-resonant terminations into our cables to eliminate the problem. We believe that the audible "Haze" or "Veils" that often overlay music in high-end systems is in part a result of cable resonance.

What he fails to mention is that there is no such thing as no resonance. Everything resonates. His "Anti-Resonant" terminations just change the frequencies at which the cable resonantes hence making it sound different - Did someone say SNAKE-OIL?

Empirical Audio has taken steps to deal with resonance in our cables. We put anti-resonant terminations in our cables to reduce this effect. To understand the effect of the anti-resonant termination, we first examine a cable without the termination.

Hmmm... so this confirms, you don't remove the resonance (you couldn't anyway) - you just change it. Isn't that what I said in my earlier post? -- Changing the resonant frequencies is one way that different cables sound different.
Bwhite's comments may be describing some of the differences I hear with premium power cables.

Nikkidanjo may be onto something where he describes cable shielding:

"Shielding the cables as they near this big rack of electronics may make all the difference. Perhaps the worst dirt is the dirt generated by your own system feeding back into itself. This could explain why shielding may help."

It may be a long wait before technology is developed that "proves" how some power cords work in our systems. Having heard significant improvements with several power cables, I don't intend to wait for a piece of paper telling me what I already know is true.

I have not tried metal outlet plates as Bwhite describes. I would not prejudge it effectiveness, until and UNLESS I tried it for myself.

I would likely believe in Mr. White conclusion, even if it failed to improve my system. Every system is different and it would be foolish to pass up an opportunity that at least one member has been successful with, especially one that costs about what some of us spend on a large soft drink.

I intend to purchase a couple of plates next time I visit Home Depot. Worse case I return them a few weeks later.
Thanks Albertporter! Please - don't expect the plates to make an improvement. They will however add a noticable and somewhat annoying brightness to your system. Hopefully this will help folks understand how mechanical resonance can play a significant role in what we hear in our systems.

Also, while you're at it, and if you feel like playing... the tightness of the screws which hold the outlet to the wall make a change as well.

After trying this with several outlet covers I ultimately decided to leave them off all together in my system. Having no outlet cover so far seems better than any other material.

Now if I can just figure out how to firm up that giggly junction box in the wall without tearing my sheetrock to bits.