Originally Posted by mus1cjunk1e
Jitter is just that -- a swaying of the timing of the 1s and 0s. That may be able to affect how the DAC reproduces the sound, but that can only go from "timing way out of whack" to "timing perfect", there's no additional coloration of the music going on. By definition, if the timing is perfect (i.e. perfect square wave) you're just going to get the exact sound from the recording, nothing more. If it's off, you're gonna get stuttering or timing issues. That's the only two things it can do. Anything else is pure placebo.
You'll have to excuse me for being blunt but you're speaking out of misconceptions, you're missing by a whole kilometer how jitter affects digital to analog conversion and you have no right to state your misleading opinions as if they were facts.
On the basics of digital audio transmission (most of it applies to spdif, but USB audio isn't too far away), here is a good beginner's introduction, if a bit audiophile minded: http://www.tnt-audio.com/clinica/diginterf1_e.html
Nick_charles mentionned (see his post 29) earlier the work of Dunn and Hawksford, here are some links:
http://www.nanophon.com/audio/jitter92.pdf (Dunn, "Jitter: specifications and assessment in digital audio equipment")
http://www.essex.ac.uk/csee/research/audio_lab/malcolmspubdocs/C41%20SPDIF%20interface%20flawed.pdf (Hawksford and Dunn, "Is the AES/SPDIF interface flawed ?")
I'd add this paper by Dan Lawry, "On jitter" : http://www.lavryengineering.com/white_papers/jitter.pdf
If you want even more reading, here is a catching account on how a USB audio receiver was designed at Texas Instruments and about what kind of problems engineers encounter in real life when dealing with that supposedly easy digital stuff: http://www.eetimes.com/design/audio-design/4009467/The-D-A-diaries-A-personal-memoir-of-engineering-heartache-and-triumph
It is scientifically established (by theory and measurements) that jitter is affecting the digital to analog conversion in subtle ways. There are indeed perfectly valid ways to measure jitter down to around 100ps at the analog outputs of DAC with overall THD+N figures below 120db.
The point of disagreement in "audio science" isn't "does jitter affect the D/A process or not ?", because it does and if you had a superhero's hearing you'd hear it without a doubt. The point of disagreement is "when does it become audible for us mere mortals ?". At that point, the studies linked to by Nick_charles offer you a strong basis to put in doubt claims to hear extra low jitter. Not because jitter doesn't have an effect on the final analog sinewave but because the distortions it induces might not be audible.
Aos was right on the money with this rant: http://aoselectronics.com/jitter_article.html