Digital
Clock & jitter
Timing specs (ps jitter, ppm accuracy) — reported for completeness, never as a fault.
Simple
Jitter is tiny wobble in the timing of each digital sample, measured in picoseconds — trillionths of a second. Clock accuracy (ppm) is how close the player's speed is to perfect pitch. On any working modern link both sit far below what anyone can hear, so the engine shows the numbers without turning them into warnings.
The theory
Sampling-clock jitter converts timing error into amplitude error: sidebands around each tone whose level scales with signal frequency and jitter magnitude. For 16-bit audio, keeping jitter artifacts below the quantization floor needs roughly a nanosecond at 20 kHz; modern DAC master clocks measure in the tens of picoseconds. Clock accuracy in ppm shifts absolute pitch — 100 ppm is 0.01%, about 1/600th of a semitone — irrelevant for playback. Interface jitter (on the cable) matters only insofar as the receiver lets it reach the conversion clock, which async USB and FIFO-reclocking inputs prevent by design.
For experts
The audibility literature is unusually consistent here: detection thresholds for random jitter sit near 250 ns for broadband noise-like jitter and no lower than ~10 ns for the most pathological deterministic single-tone jitter, while measured conversion-clock jitter in current mid-range DACs is 10–100 ps — two to three orders of magnitude of margin. A ±10 ppm crystal holds pitch to 0.001%. This is why the engine's stance is "report, don't gate": the numbers are worth knowing when comparing conversion points (a 15 ps reclocked stage has more margin than an 80 ps streamer output feeding a PLL), but presenting them as pass/warn/fail would manufacture a problem the measurements say does not exist.