Romex to your amp?

   If you have an electrician connect a direct line from the fuse box, by passing all other electrical devices you plugged in the house, the sound will be improved...

   You can do this for around $200.

Sure and by that same token you could always just hardwire your amp to that run of Romex. However that kind of limits your flexibility not to mention potentially voiding any warranty.

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