John Phillips wrote:

[1] I did the analysis of this effect some years ago for loudspeaker
cables and derived expressions for how the capacitance and inductance of
zip-cord speaker cable varied with current flow. The coefficients (of
dependence on the square of the current) in typical cases were in the 1-10
parts per billion range, IIRC. I decided they were too small to matter.

-180 dB is indeed pretty irrelevant.

Graham