"audioengr, if you started from digital out in a computer, could it compete with the best "stand alone CD players"; if you used the best DAC?"
No way. No expensive DAC will fix this. In this case, the master clock is inside the computer. It's this clock that is critical. Need to get it out of the computer and into an external box with a good power source, like a USB converter or USB DAC. The clocks used in these also have lower jitter than anything used in a computer or soundcard.
Think of the master clock as the phonograph cartridge. If you dont have a good one, there is nothing you can do downstream for any amount of money that will repair the damage that it does to the signal. In the cartridge case, its an analog signal. In the digital case, its a digital signal.
Networked interfaces are another option, but these are mostly proprietary and have poor clocks IME (Sonos etc..). You can of course mod them to change to lower jitter clocks or put reclockers after them to improve the jitter performance.
Steve N.
Empirical Audio