A listening test have been done in France with a jitter generator : http://www.homecinema-fr.com/forum/viewtopic.php?f=1037&t=29915550&p=172887105#p172887105
The source was a Marantz CD5400 CD player.
The output was the coaxial one.
A QSC hardware ABX switch was used to compare the Marantz directly feeding a DAC, or feeding it through the jitter generator.
The DACs were a DAC Zero (a low end DAC), a Zhaolu D3, and an iRiver H140 pocket player with an optical input.
Amplifier : Kora explorer 90 SII
Speakers : Triangle Antal 202
None of the listeners present could hear any difference below 100 ns of jitter.
Around 100 ns, the Zhaolu DAC produces clicks like a badly worn vinyl.
The zero first show some kind of intermodulation distortion, audible on medium / high frequencies, like female voices or piano, at a jitter level just below the apparition of clicks.
The iRiver player was the most resistant to jitter.
One of the listeners tried to ABX the Zhaolu DAC with and without 75 ns of jitter in the digital input, but gave up after three trials.
I insist that we are talking nanoseconds here, that is 100 to 1000 times the amount of jitter produced by any digital audio source, usually measured in picoseconds.