If this comes across a little aggressively forgive me, I'm in that sort of mood ...We can pray that good and precise timing was used in creation of music and that which lives in our digital format represents that. Our job then is to match that timing as closely as we can.
Getting rid of jitter is all about using an electrical equivalent of a massive flywheel; I think everyone understands how that works! The flywheel spins ALMOST at a perfect rate even if, say, the engine driving it is wobbling, or trying to, all over the place. That is what PLL, phase locked loops, which are used most of the time are all about. The more massive the flywheel, the better the PLL implementation, the less jitter presented to the DAC; anywhere else, jitter could be occurring at a ferocious level and it don't matter!
There are a number of ways of creating massive electronic flywheels, but ultimately it doesn't matter WHAT you use, it is how WELL it's been done. Naim, for example, in its latest DAC uses a number of completely independent flywheels running at different rates, and it picks the right flywheel to use on the fly -- a perfectly good way of doing things!
So, excellent or good enough jitter we now have. Next problem, is the digital input causing interference to the D/A conversion. For people to get a better handle on this, this is just another version of crosstalk! Everyone sees measured figures of crosstalk starting to drop off at 20kHz, just imagine the crosstalk then if there's a noise signal running around inside the case at 20MHz! And the poor old DAC is supposed to ignore this, I have seen pretty dreadful figures of PSRR, power supply noise rejection, for DAC's, no wonder they spew out bad sound at times!
Okay, 'nuff said ...
Frank