I got somewhat obsessed with jitter a few years back and experimented with a bunch of products that affect jitter (among other things). Like mdconnelly, I use Tact equipment: 2.2x preamp and two 2150 amps (with and without mods by Aberdeen). Unlike mdconnelly however, I noticed what I thought were meaningful differences using different digital cables, as well as with the jitter boxes in my system.
Transports included a North Star, a DIY Pro-2m, a modded Sony and stock and RWA-modded Olives, all fairly low-jitter sources. I used a Genesis Digital Lens, an Assemblage D2D, a Camelot Dragon 2/2 and (previously) a Meridian 518. All these purport to reclock and minimize jitter. They all 'improved' (to my ears) the sound, mostly by reducing 'harshness' and enhancing a sense of ease. Bass was also better defined. They sounded more alike than different, though I preferred the Genesis to the others. I'd like to hear the new PS Audio Lens when it comes out. Robert Harley's impressions of the Genesis can be found here (with his take of jitter's effects). My impressions were similar, though less pronounced:
http://www.stereophile.com/digitalprocessors/824/index.htmlWith the modded Olives, I ultimately felt the improvements, though there, weren't large enough to justify the added cost of the Lens and extra cable. In other words, I found that I could get equal-to-better improvements using that money for purchasing pricier digital cables. I've used a couple dozen digital cables, ranging in price from $100 to $3K+(yes, inexpensive digital cables can be gateways of addiction to more expensive ones). I heard differences in most of these cables, some pretty subtle, some not -- and also differences between RCA, AES/EBU, Glass Toslink and I2S. The differences manifested in resolution, focus, ease and even perceived frequency response. To make sure I wasn't imagining things, I took one of my mid-priced cables to a friend's house and blindly compared it to his home-made brew, and was relieved to be able to consistently pick out my cable (though the tension created by the pressure of my ears and credibility being on the line certainly made it more difficult than casual listening).
For a year, my favorite link between the Tact pre and amp was the Stealth Sextet. Then I woke up one morning and realized that a digital cable this expensive was kind of nuts, so I bought the upgraded battery power supply for my Harmonic Tech Cyberlight (and now Photon) cables and liked it equally well, and sold the Stealth. The Stealth had a touch more ease, while the Photon reveals slightly more detail. I suspect jitter as factor here, but don't really know, as there may be other factors involved.
I've commented before on an experience I had last year at a G2G at Rich's. We were using Shane's Oracle combo with the top JPS AES/EBU and comparing to my Stereovox XV2. In comparison, the XV2 was thin and bleached out. This was disturbing, because I wanted the XV2 to compare favorably -- after all, it was MY cable and had gotten great reviews (I bought it because the Olive only has BNC digital out). Even those eating in the kitchen commented. We substituted the Analysis Plus Oval for the XV2 and much-needed warmth returned, though the JPS still sounded better. I took the Oval home and compared it to the XV2 between the Olive and the Tact, and heard similar things, though not to the same degree, so system differences affect these things, too. I'm presently using the Tara One in that position, which improves upon the Oval in dynamic impact and detail.
So, I don't know how much my experiences with jitter boxes and digital cables relate to jitter, or to other things. There are so many things that affect the sound of digital, including power supplies and power cables and conditioners and platform supports, etc., etc. I suspect that the never-ending possibilities have in part fueled the return to one-box solutions. But now with streamers and hard-drive based options, the cable and jitter-box scenarios are returning to the forefront. Each of us has to determine for ourselves whether these
various jitter tweaks are audible and/ or meaningful enough to bother with. For me, they are.
