From this article by Liudas Motekaitis from LessLoss Audio:
http://www.forum.audiophile.org/ContentDetails.php?CID=14&ID=108
"The entire audio business of CD transports and DACs is built on the totally backward setup of the CD player containing the Master Clock and the DAC being the Slave. This results in the entire palette of innovations to lessen Jitter, starting from air drives to expensive digital cable technologies with complex math to reduce line-induced Jitter, to very carefully filtered power supplies, to all sorts of very necessary things when you want to achieve the least possible Jitter. So we have the worst possible digital scenario bringing in the most possible amount of money, because it is extremely difficult to annihilate Jitter when the CD player is the Master Clock. If you're looking for quality, this is stupid, to say the least!
"The whole setup should be different. As is the standard case in any pro-audio studio, it is always the playing device, the DAC, which is the Master Clock. The clock is located right next to the converter chips. That way, no line induced Jitter can appear. This clock signal is then taken from the DAC device and is used as the clock input of the signal source device, say the computer, the DAT player, or the CD player. Yes, in that setup, the CD player is receiving a more jittered clock than the DAC is, but that doesn't matter, because the DAC is doing the audio playing. When the Jittered audio signal arrives at the DAC, it is quantized into place temporally and is then played, in perfect synch with the clock oscillator, which is right next to it.
"But oh! In that case, you can use a $100 CD-player with a very poor power supply, a digital cable made from your average household extension cord, and still get a better sound than you'd be getting if you spent $30,000 on the best transport and digital cable! Yes, ladies and gentlemen, this is the naked, uncensored, plain truth about CD players and DACs. Their Master/Slave relationship is BACKWARDS and their prices therefore HIGH." (End quote.)
Of course there is a bit of commercial hyperbole here; he leaves out that a cheaper player may also emit much higher RF noise which, next to jitter, may be degrading the sound as well.
However, he then presents real jitter measurements:
"The image below shows the typical scenario using a CD Player and high quality DAC in the traditional way:
CD Player = Digital Master
External DAC = Digital Slave
Digital S/PDIF Cable Carries Digital Signal and Clock.
It is clearly evident that in this configuration the Jitter is worse than 500 ps.
The following image shows the typical scenario using a CD Player with a high quality clock upgrade, and whose external DAC is also slaved to the CD player, which is in principal the exact same scenario as above, only with a better clock. This is also the case when using a $10,000 transport with the best possible internal clock:
High quality CD Player (or High Quality Clock Upgrade)= Digital Master
External DAC = Digital Slave
Digital S/PDIF Cable Carries Digital Signal and Clock.
It is clearly evident that this configuration achieves less Jitter at about 170 ps.
Now we modify the cheapest CD Player we can get our hands on (in this case a JVC model) and use the external LessLoss Audio DAC 2004 in Digital Master Mode. In this way, the Master Clock is in the DAC and the CD player is connected via two cables: the typical S/PDIF Digital cable and a Digital Clock cable. The results would not differ if you used a $10,000 transport with the best possible drive mechanism or other exotic features such as Housing Metal from Mars, etc.:
Lowest Quality CD Player = Modified as Digital Slave
External DAC = LessLoss Audio DAC 2004 in Master Mode
Digital S/PDIF Cable Carries Digital Signal.
Clock Cable (50 Ohm Coaxial) Carries Clock Signal from DAC to CD player.
You can clearly see that this configuration achieves the least possible Jitter at less than 60 ps. Due to noise resulting from the ADC conversion process, it is not possible using this method to make any judgement on anything less than around 50 ps."