Just looking at your oscilloscope plots, I would say you have plenty of triggering issues - this would explain why you get bimodal distributions and distributions that look a mirror image of each other.
You would be much better served by analysis of the final analog output of the DAC - any jitter will show up as distortion of the known digital input signal.
I don’t believe they are triggering issues. The trigger error is something like 1-2 psec. All of my products don’t have the bimodal shape. Even the bimodal is only maybe 10 psec between peaks. Insignificant.
I don’t want the DAC in the picture when I’m testing my various interfaces. I want to measure the digital jitter directly.
Steve N.
Empirical Audio