A/B testing is something I take w a grain of salt. First, I don't pretend to have a golden ear and often struggle to hear differences between interconnects, power cords, etc. So, as an example, I might struggle to pick out the difference between a WW platinum and a WW gold XLR running from my 2300 to my 501s. I might also have a hard time telling the difference from WW gold to WW silver....and silver to eclipse, and eclipse to equinox....on down the line to their $70 Luna cable. Does this mean that Platinum equals Luna? Of course not. And, when multiplying the difference times every piece of gear in our system, the results speak for themselves.
I think of it in terms of bicycles. Many friends give me a hard time over spending lots of money and time on upgrading to parts that are lighter weight. Why would anyone spend $500 to save 40 grams on a seat post, or spend hundreds of dollars on carbon and titanium screws and bolts that are used to rebuild derailleurs, etc only to save a few grams? ...the list goes on and on. Could I tell the difference on a long climb by only swapping out the seat post....no. But, after it's all said and done my bike weighs 7-8 lbs less than it did before taking dozens of steps to save weight a few grams at a time...can I tell the difference here.... Without a doubt....