How to A/B Test Power Cables & Interconnects?

I think the best way to A/B power cables is to first ask yourself, have I spent at least $3,000 - $5,000 on acoustic room treatments, and I would even go to $10,000.  If your answer is no, then worrying about your cables is a waste of time ... it is not the roadblock to the best sound. 

That out of the way, unless you can get a friend to swap them for you without telling you which is which, it is unlikely you will subjectively test your cables and come to an accurate conclusion, even about your own likes.  Ya, sure, tons of people here will disagree with me, but if you don't believe me, go to an audio show, go to all the rooms and listen, don't ask how much anything costs, don't even look too closely at the equipment, and write down your impressions. Listen closely to the music, IGNORE the sales person trying to plant thoughts in your head. Then compare your notes to the "audiophile" press. Almost without fail, they will wax eloquently about the most expensive systems .... you know $200,000K of fancy equipment in the equivalent of your mom's basement .... hard walls (and in hotels usually cement ceilings), little to no room treatment, maybe even some strange shaped rooms. I don't care how good your equipment is, if the room is poor, the result will be poor. Perhaps not Bose poor, but a properly treated room for 1/10th the price can easily sound better (and often does).

Some of the cable guys are pretty smart. They will put a ton of work into the acoustics of the room .... and it will sound really good. They will say it is their cables ... it is not. 

It is your money though. Do you want sound or jewelry?

I think the "aholer" in this thread is painfully obvious.


millercarbon1,805 posts10-01-2019 9:34pmWouldn't it be a whole lot more honest if people like aholer would just come out and state clearly up front whether or not they are capable of hearing? Instead of hiding behind what someone else says, take responsibility. If you hear it, say so. If you don't, admit it.

Why the dishonesty?

Do you have anything to add to this conversation, or are you just harassing members on this forum again?

My post clearly discusses how to A/B (i.e. get someone to do it for you so you don't know), then it illustrates how bias enters into the results of so called professional reviewers.


clearthink914 posts10-22-2019 1:17am
roberttcan"I think the best way to A/B power cables is to first ask yourself, have I spent at least $3,000 - $5,000 on acoustic room treatments, and I would even go to $10,000."

The cost or expense of room treatments is unrelated in form of function to A/B'ing power cables if you cannot see that truth you are more confused than even I thought.

If it makes you happy, and takes away worry, it is money well spent. When you spend that kind of money on a system, you want it to look nice as well. 

Are your receptacles in separate junction boxes each with their own run back to the breaker box or are they in the same junction box with the grounds tied together. Having multiple grounds is generally a recipe for noise, but if you are using XLR, it will likely never come into play.


"I also did two home-run circuits, 10awg romex, matching phase, Oyaide receptacles. "

If you have separate junction boxes for the receptacles, then I would assume the grounds are different (at the receptacle). 

All equipment has either intentional capacitive connections and/or parasitic connections from internal circuitry to case-ground. Without your equipment connected, except for the AC, those grounds connect back at your electrical box as you have it wired. As they operate, they inject signal into the ground, which is now separated by two long wires which means that ground on one set of equipment is going to be different from ground on another set of equipment. That ground difference is injected into the connections between your equipment.

As you are using balanced connections, fortunately most of that noise is going to be eliminated, but keep in mind, that noise tends to "pump" with the signal, so your floor with no signal may be really quiet, but that does not mean there are no noise issues.

If all the equipment has the same local ground, then the ground noise is only injected over the lengths of the power cords, not the length of the home-runs (2x) plus the power cords. As the injected current will be the same in both cases, the longer resistance of the added 2x home runs will make for a bigger noise signal voltage.

That part is easy. Just bring your two home runs into the same junction box connecting the ground from each to the J-box metal, and then to each receptacle. 

I am not an electrician either, though was once fairly handy with the electrical code, but that was a while ago. Just went down to my panel, as expected, I have a dual single pole breaker that both trip at the same time (not a common 2-pole), however, perusing HD website and I can't find this style any more, so that tells me that maybe they don't make them any more?

Perusing the web, it does not appear that doing this is verboten, but, like my installation, you would (for residential) need a breaker that disables the circuit at the same time. That could be tough with a breaker panel, easy with a ganged breaker in a box. 

The easiest thing, that would not confuse inspectors, would be to have two outlets close together and just tie a ground between the two.


builder3203 posts10-22-2019 6:26pmrobert, first, I’m not an electrician, so take anything I say with a grain of salt. That being said, I have been in residential construction for 30 years. I’m in the Pacific NW. I’ve never seen an electrician here use a metal box in a home without good reason. Something heavy, like a ceiling fan, or remodel work in an older home. I wouldn’t think audio AC cables would rise to that level, given a quality box like a Pass & Seymour, etc.I wouldn’t run a ground like you describe. An electrician may or may not, I’m not sure. Generally, from my limited understanding, it’s not advisable to just bond grounds together at random. I’d have two separate circuits, or only one. 

By code, they (grounds) have to be all connected at the panel to a single bus-bar do they not?

Perhaps obsolete, and I wonder if regional, but I am still seeing more metal boxes even in new construction, in north east U.S. and Canada, but pretty much all plastic with integrated vapor barrier for the exterior. Are we talking the same thing? i.e. ... https://www.homedepot.com/p/2-Gang-Drawn-Device-Switch-Box-with-Bracket-685SP/100154820

Sounds like you know this well. I would be interested in your insights ... and how it relates to mechanical as per the next paragraph.

While metal boxes have higher potential for "liability", if they are improperly grounded and a live wire touches the box, and a person touched a screw that attached to the outlet cover that attached to the box, then yes they could get a shock. (Or you cut the romex on the sharp metal). On the other hand, with people hanging literally pounds of audiophile AC cables off them, and multiples at that, the significantly higher rigidity of metal could balance out any benefits of plastic.

That said, for the DIYer, plastic can be safer (and easier), and since the gauge used was 10, it should be easy to just run each ground to the separate receptacles (in the same j-box), and then run a ground wire between each receptacle so the grounds are at the same potential.

Big power amps with linear supplies can draw peak currents off the AC line in the 10's of amps. Depending on the gauge of your run, even with 12 awg, that can lead to significant voltage drop and essentially modulates your AC line which leads to distortion products that are a function of 1x line frequency, 2x line frequency, and the frequency of the music. It all depends on how sensitive your equipment is to noise on the AC lines.


The problem will be which "pro". Both electricians and inspectors can run into knowledge gaps when you are doing something out of the ordinary. I have had to deal with that a few times.

Whether you can slide by a single ground wire would come down to the size of the breakers. Typically the ground wire must be equal to the size of the conductors, and since you have 2x conductors, you would need 2x ground wires of equal gauge or the breakers rated for less current than a single run of the ground wire. Better and safer to connect both.

builder3206 posts10-22-2019 9:07pmWhy not just have one circuit? There’s no load to speak of. A single run of 12 wire and whatever outlets and box you care to use should be more than adequate. 
On a separate note (and run this by a real electrician), I’m wondering if there’s any reason you’d be prohibited from having the two separate circuits, but only use one of the grounds for both. Leave the second ground unused in the back of the box. May be reasonable, may not be, talk to a pro.