It’s the jitter on the S/PDIF coax output of the Oppo:
https://www.audiocircle.com/index.php?topic=154408.0
The same jitter will not be experienced when using the internal DAC.
It can be fixed and even improved however:
If you add a Synchro-Mesh reclocker and a good BNC coax cable, the Oppo jitter is reduced to ~7psec at the end of the cable, rather than the 800psec of the Oppo and cable alone. More than 100X less jitter. You will not find ANY transport with jitter this low.
Jitter is ALL that matters in a digital source.
Steve N.
Empirical Audio