Romex to your amp?

Solid copper makes a great power cord. The only reason you won’t find one commercially is that they need to use stranded wire to get UL approved. So cords like this are DIY only.   You should be able to improve on the Romex design by taking it apart.  Twisting the positive and neutral wires together,  then wrap the ground with a loose twist (every 4-6 inches) the opposite way.  Hook this up to a pair of Sonarquest red copper plugs and IEC ($20 shipped) and you have a power cord much better than the throw away cable that came with your system.     Experiment some and if you like the sound you can upgrade your next pair.  Then the sky (and price) is the limit,

The reality is that a power cord made from 12-14 gauge solid copper is pretty good. The problem with this is that this wire is not UL approved for cords and is very inflexible indeed. Most electrical Romex runs to the outlet in question are 20-40 feet in length. The power cord adds an additional 6 feet or so, so this is a small percentage of the entire run. It turns out that typical "rubber" stranded copper power cords have significantly higher inductance than the Romex in the wall, even at the same wire gauge, so these are not recommended. Empirically, stranded rubber cords have been demonstrated to limit transient high-power currents (dynamics) compared to solid copper conductors when supplying power to typical audio power amplifiers.

It is fairly easy to build a serviceable cable that will minimize power cord inductance. A simple 3-conductor twisted cable from 12 AWG solid THHN from Home Depot yields a very high quality power cord, although it is so stiff that it must be bent to the desired shape. It is actually superior to the Romex in the wall because the twisting and close proximity of the insulated conductors will reduce the inductance by magnetic coupling between the conductors. In the optimum configuration, the Hot and Neutral are twisted together and then the ground wire run beside or wrapped around them. The trick is to design a flexible version of this cord with the same characteristics. This is why some of the expensive cords are actually good designs, although more than $500 is unreasonable to achieve a good design.

http://www.empiricalaudio.com/computer-audio/technical-papers/myths-and-snake-oil

Dweller.
Like I mentioned its not all about the juice. The resistance loss of an additional 6 foot piece of wire of any reasonable gauge and a few plugs is not as important as filtering out the RFA interference.

But........If you would take apart the last 6 feet of Romex, braid the leads like I described, then solder it to your equipment. You would definitely be on to something!

Millercarbon
Is your house wired with 5 nines copper from your private generator? You do know you have 50+ feet of Romex in your walls behind your stereo.
The trick to power cords is they filter out some of the high frequency interference. Its not that the 3 foot cord of some ultraconductive big gauge wire amplifies the voltage you lost going thru the first 50 ft of Romex. You can get 95% of the way there just by twisting the positive and neutral AC leads tightly and have a loosely wound wire that connects to ground that acts as a shield. Then add some plugs that are better than the cheap injected molded nickle plated crap.
For my DIY power cable I decided against using Romex. I was seriously thinking about it but the stiffness mentioned stopped me. I tend to play around with my system too much and did consider the solid wires being brittle. But if you just plug things in and stop messing with it will be OK. Its more about the design and the way you plug your components in. Ended up going with some 12 ga silver plated Teflon jacketed mil spec wire instead and some pure copper Sonarquest plugs . It works.

Daveyf

If we take this scenario one step further, and agree ( or not?) that Romex is the material/cable that is the limiting factor in the power supply SQ to our gear ( particularly our amps) then the question becomes how does a different kind of cable from the wall to the amp ( or other gear) better the sound of the cable in the wall. 

Sorry but I don't agree that Romex is bad.  Romex in your home is fine (good thing).  That happens between the hundreds of other miles between you and the power generating plant and your neighbors on the same grid using hair driers and noisy electronics is another story though.

Unlike what goes on in audio, AC power is easy to comprehend.  You don't worry about high or low frequency effects of the wire or if you need 6 nines pure copper.  All you need is a perfect sign wave at 60 Hz (only). You may have a small voltage drop of a few volts between you and your transformer but that is inconsequential.   All power cords do is give a chance for some of the RFI to dissipate in the last few feet of its thousand mile journey to your home on the grid.

Electronics and power cords do not need to be UL listed. Certification is an optional process that costs $5,000-15,000 of dollars per model and is only good for 5 years. The only reason large manufacturers do this is because many retailers and contracts specify certified products only. Clearly very few (if any) boutique power cables and audio components are certified.
There is nothing wrong or illegal about solid core power cables. They were sold by a number of manufacturers in the past and Anticables still only sells solid core power cables. You just need to treat them a little more gently and don’t beat and twist of them like that orange extension cord you have in your garage. Properly constructed with decent plugs solid core can sound great. Easily better than any stock power cord and they can also compete well with the big bucks cords. The best part is you can put one together for <$50 (a little more if you want to sheath it and make it look professional).

But don’t take my word for it. Check out this PS Audio blog.
https://www.psaudio.com/pauls-posts/my-first-cable/

https://www.psaudio.com/pauls-posts/cable-geometries/