Audiophilepure

https://www.stereophile.com/content/aurender-n50-serverstreamer

Footnote 1: Aurender describes the clock architecture as “FPGA-disciplined, OCXO-referenced, VCXO topology.” The OCXO (oven-controlled crystal oscillator) provides a precise and stable reference, while the VCXO (voltage-controlled crystal oscillator) is driven by the OCXO and provides a high-spectral-purity clock signal. The net result is a precise clock frequency devoid of slow or fast frequency drifts.Footnote 2: For example, if the clock frequency drifts up and down 200 times a second, the result will be that a 1kHz tone will get two additional spurious tones: one at 800Hz, and one at 1.2kHz (1kHz ±200Hz). The relative magnitude of these spurious tones compared to the main signal increases as the frequency drift gets bigger. Search for “Audio Precision TN-23” if you’re interested in a detailed explanation of jitter in digital audio systems. Also see this 1993 article in Stereophile.