It is not recent. The article was published in 1995. It is posted on their site now. That aside, it is a faulty test. A person in the letters section explains why:
Cable physics
Editor: I am writing regarding Ben Duncan's "What a Difference a Wire Makes" (December '95, p.95). The time-domain results shown are hardly surprising, especially given that his test signal "representing a music transient" bears little similarity to a musical signal at all.
Musical signals have an unmistakable amplitude envelope, a fact well-known to synthesizer designers. Percussive sounds may start with a rapid onset, but they all end with a controlled decay. The end of the [1kHz] toneburst used in his tests bears more similarity to a squarewave than to a musical source. The maximum slew rate of a sinewave occurs at the zero crossing, and this is where the tone burst suddenly ends. For example, look at his fig.7 (Vol.18 No.12, p.100). Cover up the waveform to the left of the "4.00m" mark. Note that the end of the toneburst not only looks like the rising edge of a squarewave, [this is a visual illusion due to the large vertical amplification used in BD's graphs—Ed.], but also the circuit behaves as if it were (and for good reason), with harmonics similar to those shown in my fig.1.
Cables with greater inductance and amplifiers with lower damping factor will have a higher impedance at higher frequencies, which permits greater ringing with transient signals. The end of a 15kHz toneburst could certainly be considered "transient" since its slew rate is 15 times greater than at 1kHz. Whether or not the >100kHz ringing observed is "common" is unproven without a larger sample of amplifiers. Whether it makes an audible difference is yet another question that perhaps bats could answer.
The amplifier I tested does not exhibit this "imperfection" even at frequencies greater than 15kHz, in spite of the amplifier's relatively large negative feedback. On the other hand, this amplifier's damping factor remains constant and high across the audio spectrum. So which will make the greater difference—the amplifier, cable, or speaker? If Mr. Duncan had used a different amplifier, the cable effects at 15kHz would have been masked less by the amplifier's artifacts.
Even if we were to accept a toneburst with no amplitude envelope control as a possible musical source from an electronic instrument, no evidence is shown that the measured effects are actually audible. If they were in any way audible, then I'm certain that data would have been prominently displayed. Then the phrase "meaningful differences" would be undeniable. If no one can hear it, how important is it?
I can find nothing in Mr. Duncan's results that suggests "logic" concerning special cables for mains. I have never seen current waveforms into power supplies that even remotely resemble an isolated double-sine toneburst. The fundamental frequencies involved are so low (50Hz/60Hz) that even the harmonics will not be profoundly affected by mains-cable inductance (even without considering the tens of thousands of microfarads of filter capacitance that follow in a typical power supply). What degree of real improvement could be expected by changing the last meter or two of cable at the end of several kilometers of mains wiring?
Mr. Duncan's data concur with mine: The effects of a speaker cable, though measurable, are small compared to amplifier artifacts. Once again, we are left with clearly measurable differences between speaker cables, but no proof that these differences are audible.—Fred E. Davis, Connecticut