Cables for Specific Applications
This is what I think when I building cables.
1. If we were to use this for analog audio. I would use Braided Wires like I just told you. They have low capacitance. You can get this type of capacitance with Coax cables but they tend to get much more expensive.
2. Speaker wires handle analog audio, but this thing has to handle higher current. Do consider using fatter wires. Note doubling up smaller wires are fine too. Just need a little thinking ...
Personally I do not believe we need heavy shielding for the above applications. I have operated audio devices in Tokyo ... Radio Busy City ... and had no problem with shielding. Radio signals cannot cause enough current in the wire to be significant. All the RF problems comes from the amplifiers picking up RFs. Thus, you should concentrate shielding on your amplifer modules.
You must have heard some crazies using a ceramic pylons to hold up the speaker wires above ground. They probably does very little. Electrons will jump to "earth" if they are in high potential state. However, I assume speakers don't run at 15000V. Effectively, the result of pylons are very minimum.
3. Coax cables are not really cables. They are what we call waveguides. They are designed to handle very specific frequencies. You will get efficient propegation at harmonic frequencies of the cable. (Note there are multiple harmonics.) So I believe they are less suited for differential signals/audio analog signals.
4. Coax cables can handle wonderfully for certain specific frequencies. So this is good for DAC digital signals which have somewhat singular signals. Since it attenuates non-harmonic freqs, it will lower RF pickup more effecitively. On top of that they are shielded. RF on digital signal can be significant. Note digital signal has already lost some integrities during the recording stage. Any audio crazies know that no analog audio can be completely converted to digital "exactly". Getting RF there can degrade the signal on top of that.
Please note the loss of integrities in analog -> digital conversion is NOT major problem. If you are worrying about this, you are not audio enthusiast; you are audio-crazy / audiophiles. (Believe be this is not supposed to mean pleasantment.
5. Nothing is better insulator than a vacuum. ... We cannot have portable vacuums like in StarTrek. So go for Teflon.
6. Signal travel at the surface of conductors. Electrons likes to repell each other, so they try to stay far away as possible according to the Laws of Physics. Only place to go is not to spead out in the conductor but to go to the surface of the conductor. So I choose cables with bigger surface area. In other words, I choose stranded conductor wires. Solid conductors will have smaller surface area.
Personally, I did not hear much difference. But I did it anyways for good measure. Only the actual good thing from doing this was the bendability
But then bendability is very important for cables. Hopefully someone hear the difference. ...
7. Lastly, Connector contacts must be gold or tin plated. Gold does not tarnish and stay very conductive. Tin plating can go very little on oxydation. You can get gold plated parts for almost the same price as non-gold plated parts, maybe thanks to Russian Gold.