In the converter world, 99% of converters require a high speed clock. This PLL circuitry generates high frequency clocks, from a low frequency rate (typically, you have to generate 24.576MHz from your 48kHz wordclock.
this is usually in your converter unit, not in the big ben unit.
All PLL's, no matter how well designed with introduce jitter to the high speed clocks. the only way to avoid Jitter is to use the crystal integrated into your converter unit.
There's a great paper by Dan Lavry on the effect of Jitter on audio clocks. His research shows that the first effects that jitter have is on distortion/noise at high frequencies... i.e. your high frequencies will begin to have higher THD+N than the rest of your audio.
It makes me ponder if there is a school of thought that says that the music *sounds* nicer with a little distortion at high frequencies, even though friends will an oscilloscope would be having heart attacks?
cheers
/R