Quote:

He says that due to a structural problem with spdif (hence the stigma of spdif being associated with jitter), the data and the clock sync get messed up.



He elaborates more about this on the second page I linked. Basically the way the data is encoded it relys on certain voltages to represent those states. What happens is there are some instances where if too many 0's follow each other there is a delay before a 1 can be represented and this messes up the clock information. It's quite a bit more complicated than that and my backround is in CS not electrical engineering.

In any case after reading through his pages, there are lots of places where jitter gets introduced. The bottom line is, it's impossible to get 100% time synced data (since no timing crystal exists with that kind of accuracy). From the original recording, all the way through to playback you will be picking up jitter.

So back to the all important question. Does this really make a difference? Here is what he has to say about that.

Quote:

In my personal experience, and I would dare say in common understanding, there is a huge difference between the sound of low and high jitter systems. When the jitter amount is very high, as in very low cost CD players (2ns), the result is somewhat similar to wow and flutter, the well known problem that affected typically compact cassettes (and in a far less evident way turntables) and was caused by the non perfectly constant speed of the tape: the effect is similar, but here the variations have a far higher frequency and for this reasons are less easy to perceive but equally annoying. Very often in these cases the rhythmic message, the pace of the most complicated musical plots is partially or completely lost, music is dull, scarcely involving and apparently meaningless, it does not make any sense. Apart for harshness, the typical "digital" sound, in a word.

In lower amounts, the effect above is difficult to perceive, but jitter is still able to cause problems: reduction of the soundstage width and/or depth, lack of focus, sometimes a veil on the music. These effects are however far more difficult to trace back to jitter, as can be caused by many other factors.