This thread can go on forever in this vein. I've tried to contribute what I can, but I'll just start repeating myself if I go much further.
And, for some here, it probably doesn't matter what I say. Guys like leeperry want to believe way more differences exist than survive even the most carefully run blind listening tests. And guys like USG want to keep finding exceptions for reasons I don't really understand.
As I said in the article, some of this isn't black and white. Jitter is a perfect example. I can't definitively say how much jitter is too much and even the methods used to measure it are not well standardized.
But I have a lot of confidence in well run blind studies like Meyer and Moran. Their A/D -> D/A hardware certainly had some jitter, but obviously, nobody could hear it. They also couldn't hear the interconnects, the power supplies, all the op amps, connectors, power cords, etc. There's just too much similar evidence out there to try and dismiss all it on any rational basis. But I know many still do. That's their choice and they're welcome to probably spend more than they need to on audio gear.
And, leeperry, look up Samuel Groner's huge paper on op amp distortion (it's a big PDF) and search on Audio-GD. He was probably laughing his butt off the Audio-GD discrete op amps measured so horribly bad and his comments were to the effect of "I can't see why anyone would ever use one". I have no doubt they sound different--probably in the way the little flat music box in a Hallmark greeting card sounds different. The chip in the greeting card could probably give Audio-GD's designs a good run. They're that bad.
