Uh, listening through a Dell and a Mac and headphones?
What? About ten cents worth of audio "equipment"? 
And the first thing we do in our lab, before making a publishable measurement, is calibrate the measuring equipment.
Did they test whether the listeners (the measuring equipment) could actually discern the difference between measurably different speakers or headphones?
The article falls back on the Golden Ears canard. 90% of people can, with some attention and training, learn to listen carefully. 90% of people do not listen attentively or carefully enough to notice differences that would be obvious to experienced listeners.
Would you hand a Stradivarius and a $55 ebay violin to 7 students pulled out of a college football stadium, and declare "Objective Test Proves Stradivarius Sound Quality a Myth"?
The ethernet cables may or may not sound different. They do measure differently, however (see the Ars cable test). The only way to test is a) with proper measurement equipment and b) by not contaminating the sample (running it through poor quality outputs like laptop DACs and headphone amps).
What an utter waste of time, and a sad discredit to the otherwise important work of JREF.
