Comment Any conductor is fine... (Score 4, Interesting) 101
So long as the conductor conducts and only adds minimal inductance / capacitance - anything is fine. You will just be power limited with poor conductors. That being said, conductors with higher resistance can pick up more external noise. This is because the low impedance signal is no longer low impedance. But in a clean environment this will not be an issue.
The article explains it poorly, but from the image it appears that the signal being referred to is the signal between audio source and amplifier. So a low impedance source connected to a high impedance sink. Resistance will not play much of a role as there is no power being transferred. It would be interesting if the same results were observed when using an older amplifier where the inputs do actually draw some power.