The other main rule concerns not looping antenna signal cables (twin-lead), which tends to induce the same types of noise as a ground loop by making them antennas themselves. Electromagnetic induction; it’s a blessing, it’s a curse. (If you don’t know about it)
As to the quality of cables: A poorly made cable can cause noise issues, but there’s no real advantage to spending a fortune on them. A common misconception is that the more expensive the metal, the better the cable. Wrong. Gold is used on connectors because it doesn’t oxidize, not because it’s the best conductor of electricity. It’s quite good, better than nickel and chrome, but actually a bit worse than silver and copper. Forget platinum—it sounds sexy, but is about 20th down the conductivity list.
Copper wire with gold connectors are the best combination; but again, don’t listen to the boutique audio sales propaganda. There are plenty of cables in the $10 to $20 range—or even lower—that will serve just as well.
One thing you could check for, though it’s mostly an issue in high-impedance (higher gain/voltage, aka Hi-Z) applications, such as with guitar cables, is that they aren’t microphonic. Poor, or loose shielding and other factors can actually turn physical shocks into audio signal. I’m not kidding. I’ve experienced this only once in my life with component-connecting cables and that was for a turntable. But if you’re noticing odd noises that seem to be in time with the bass or vibrations, give the signal cables a hard tap with a finger (with the equipment powered on) to see if this is a problem.
One more wire issue: size. While larger guage wire can actually help an amp work a little easier and cooler when driving speakers by lowering cable impedence (resistivity), the impact on signal cables is negligible. That is, it's inaudible to anyone who didn’t pay a lot for a fat wire and needs to hear a difference.
Ever wonder why the walls of your stereo receiver and other electronic devices are metal, when it seems like everything else in the world is made of plastic? It’s not for tensile strength, it’s to block incoming and outgoing RFI (radio frequency interference). Any conductive material tends to block RF signals and shunt their charge to its surface. Indeed, the shielding on cables work as Faraday cages.
But the practical implementations (not lining your TV room with copper sheathing) of Faraday cages can only do so much, so you might need to lessen the strength of the signals they must deal with. I’m talking portable phones, cell phones, Wi-Fi equipment, and even computers.
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