Effects of Inductance and Skin-effect in a speaker wire.

[E-Stat]

Here is a reference where the phase shift and group delay are talked about in wire and where the number I used above came from:

The conclusions of that study using dummy speaker loads are worth considering:

"The fact that the reported observations can be modelled so easily does not, of course, constitute ‘proof’ that no new and unknown cable properties can possibly exist. Nor does it ‘prove’ that cables cannot affect the perceived quality of audio signals."

Indeed.

rw