Quote from the text linked above "Experiments were carried out in the listening booth or studio that each listener had offered. The examiner only brought there a personal computer with a digital audio interface and a mouse and each listener provided his or her favorite DAC, amplifiers and loudspeakers."
Knowing what we know about USB DACs and interfaces between portable computers and DACs, it's no wonder that jitter differences were masked by this inferior and highly variable interface methodology. Also these tests were done in 2005 when the quality of USB DACs was far inferior to today.
p.s. audiophile and high end audio always use real life listening test.
For further reading on this subject, the audibily of jitter:
TAS (June/July, Issue 182)
The Effects of Sampling Clock Jitter on Nyquist Sampling Analog-to-Digital Converters, and on Oversampling Delta-Sigma ADCs," Steven Harris, JAES, July/August 1990, Vol.38 No.7/8.
p.p.s. when are you going to spend time on something that you have interest in. It's clear that it's not hifi.