Buffer除不掉jitter？

上回說到DIY Audio上一堆人用PC做訊號源，但後面的音響設備都不怎樣... http://records2ear.blogspot.com/2009/10/diy.html
這會來了個老兄，用的機器就高檔多了
http://www.diyaudio.com/forums/pc-based/150343-computer-based-hifi-13.html#post1973789
DAC還用了Chord QDB76！這隻可不便宜啊...

而且號稱用上buffer及精準的clock能將jitter壓在3ps之內！AudioPrecision的儀器也不過到4ps而已勒～
那，真的能消除jitter嗎？

這老兄試著用光纖輸入，因為設計者建議用光纖，能避開前面來的電氣雜訊，
沒想到...聲音比同軸電纜差...
http://www.diyaudio.com/forums/pc-based/150343-computer-based-hifi-13.html#post1974778

這...用了buffer隔開前面的jitter，再用精準的clock送出，照說用光纖不至於會比用同軸電纜差啊？
難道光纖的資料會錯？
還是Chord唬爛？
許多測試顯示Toslink會導致較高的jitter...是這原因造成的？
當然，我不知道發文者所說的比較差是怎麼回事，也只能相信他的耳力了...

其中他提到的這一篇的後續
http://www.zerogain.com/forum/showpost.php?p=15714&postcount=21
發文者嘗試比較光纖與同軸電纜，結果也說光纖比較差，差在哪？
Hmmm....somethings wrong, everything sounds terribly "thin". No body, no warmth, very clinical. Also, when the music moves into the treble registers it's very bright - harsh even. Someone please pick my ears back up off the carpet  Seems to have great resolution and detail though but I really can't live with that harshness.

Next up, my Apogee Wyde-Eye cable which I terminated with RCA Bullet plugs, also straight into the DAC64:

Ahhh...that's much better, all the body and soul of the music has returned   Lots more drive and punch in the bass aswell and none of that horrid treble harshness. Just a touch less detail though, things ever so slightly less well defined as with the TOSlink but of the two the RCA Apogee cable beats TOSlink hands down. It's no contest.
這...或許會有些值得玩味之處...
音響的表現，必須看整體，某個環節偏左，若是補上個偏右的環節，那就拉回來了。
不知這位仁兄的狀況是否是如此？
何以我如此推論？
因為這句
 Just a touch less detail though, things ever so slightly less well defined as with the TOSlink
較多的細節，代表者較正確的訊息（當然，這是指整體全頻段的細節，而不是只有高頻）；
而這位仁兄說比較差的部份，其實是指整體平衡，這該是後面機器的問題...
精準乾淨，就會讓人覺得比較多高音與較少的低頻，這位仁兄的系統該是偏一邊了...
許多人習慣於一堆低頻，卻沒想過“如臨現場”這詞的意義...


再請DIY audio上這位解釋差異何在
http://www.diyaudio.com/forums/pc-based/150343-computer-based-hifi-13.html#post1975644
只差一點點...
I would say lack of depth in the mid to upper frequencies was noticeable. I listened to bit of KD Lang's Ingenue album, and the depth and articulation of her voice seemed to suffer a little. Not a huge amount, but enough for me to be sure there was a difference...
倘若是Toslink jitter先天就比同軸電纜差很多(在他提到的另一篇裡），應該有相當明顯的差異才對，而不是這麼一點點...