My speaker's manual says the following:

> Please always use a good quality loudspeaker connection cable from an audio dealer. To prevent impairment of sound quality, we recommend cables with cross-sections of at least 2.5 mm² for lengths up to 3 m and at least 4 mm² for lengths above 3 m.

Interestingly, the table present in the printed manual is not present in the one on the internet. IIRC, recommendation for 100W up to 3m was 3mm² or 4mm² at minimum.

From what I looked at, 14AWG is ~2mm² and 16AWG is 1.3mm². Way too skinny for what the manufacturer says.

Unless you're running speaker cables parallel to some power cables, shielding is not a requirement from my experience. The cable I use is at [0]. I have a roll like this. Mine is thicker than 2.5mm² though.

[0]: https://m.media-amazon.com/images/I/71Jr0vhSTsL._AC_UF1000,1...

> To prevent impairment of sound quality, we recommend cables with cross-sections of at least 2.5 mm² for lengths up to 3 m and at least 4 mm² for lengths above 3 m.

This is just a unit issue. See:

https://www.engineeringtoolbox.com/wire-gauges-d_419.html

Those numbers are also ridiculous. They’re recommending 13AWG or higher for a 3m run. That’s about 20 feet round trip, which is about 0.04 ohms. The speaker should be 8 ohms nominal, but let’s call it 1 ohm at some very audible frequency to be conservative. So you might lose 2% of your power or maybe 0.1dB. Keep in mind that you cannot hear frequency-independent attention at all (the volume knob fixes it), so you’ll only hear the frequency-dependent part, which will be smaller, and your speaker plus room already has frequency dependence far in excess of 0.1dB. Note that the speaker power doesn’t even factor in to the calculation — as you supply more power, you’re increasing the current and voltage accordingly, and the effects cancel out.

At very high power you may care about heating. That recommended cable has an NEC ampacity of 15A or more, and 15A^2 * 8ohms = 1800W. Derate a bit because you’re at higher frequencies than 60Hz and you are just fine — in fact, the voltage will become a safety problem at silly power long before the resistive heating matters.

I will admit that there is a good reason to use at least 18AWG cable or so: speaker cable terminations are utter crap, and the crappiness seems to get worse as the fanciness goes up. A thicker wire is more likely to survive being terminated, within limits.

Buy some 16AWG two-conductor CL2 or CL2R or CL2P cable at your home improvement store and be done with it.

> Unless you're running speaker cables parallel to some power cables, shielding is not a requirement from my experience.

I have never heard mains hum coupled from a passive speaker cable. That’s not really a thing — there just isn’t enough power to make it audible under normal conditions.