Whether or not a dac is transport sensitive depends, in my opinion, on the dac. The only dac I've heard transport differences on was a Cyrus DAC-Xp. The QBD76 you (the op) plan on using is not transport sensitive (I used to own one), I tried about 10 different transports (mac, cd, dvd, bdp) and they were all the same. Optical was used in each instance.
As to could anyone tell the differences between competent (bit perfect) transports through a dac that had competent jitter rejection, I am sceptical. The only way to prove you can hear a difference in my opinion, is via a double blind listening test. There have been documented jitter audibility double blind tests done in the past, the most comprehensive I've seen sadly appears not to be hosted online anymore. The following quote from another forum contains some of the results of that listening test: "
From the lead author of the jitter paper
This is the reply I received - in its entirety.
================================
Quote: Dear Jim,
Thank you for the e-mail. I suppose that you read our paper titled
'Detection threshold for distortions due to jitter on digital
audio(
http://www.jstage.jst.go.jp/article/ast/26/1/50/_pdf).' Before this
paper was published in the Acoustical Science and Technology, we had
published another paper 'The maximum permissible size and detection
threshold of time jitter on digital audio.' Unfortunately, it was written in
Japanese.
In our first experiment, which was reported in the Japanese paper, we used a
fixed listening condition and fixed materials. All of 14 participants were
university students without any special training. The audio system that we
used consisted of the following equipment.
D/A converter --- SEK'D ADDA2496S
preAmp. --- Luxman C-7
main Amp. --- Luxman M-7
loudspeakers --- DIATONE DS-205
They costed about $10,000. I don't know if they belong to high-end or not.
All participants could distinguish between sounds with and without time
jitter when the jitter size was 9216 ns. A few could when it was 1152 ns. No
one could when it was as small as 576 ns.
There was a question, however, if the result would depend on the listening
environments and the skill of the listeners. That is why we carried on the
second experiment. This second experiment is reported in the paper, the one
that you probably read.
Listeners in the second experiment were all professionals, audio engineers,
recording/mixing engineers, musicians, etc... Sound materials were selected
by the listeners so that each listener could use his (her) familiar
materials. The experimenter (we) visited the listeners’ studios or listening
rooms so that we could use listeners’ own DAC, amplifiers, loudspeakers and
headphones. The system configurations, therefore, varied among listeners.
They were mostly mid-end or above, I suppose.
As you can find in the paper, some listeners could distinguish the sounds
when time jitter was 500 ns. It could not be detected, however, when the
jitter was as small as 250 ns.
In both experiments, there was considerable difference in listeners’
performance. I don’t know, however, if it was because of their audio
experience. We had expected much better performance in the second experiment
because the listeners were professionals and they could use their favorite
environments and materials.
Our conclusion up to now is that the normal hearing listeners' detection
threshold for time jitter in program materials is several hundred ns.
I appreciate that you are interested in our paper. Thank you for asking
questions.
Best wish
--
ASHIHARA Kaoru
================================
So in expt 1 they had a range of 9000 -> 1152 for detection i.e a range of 1 - ~9 in terms of detection ability, none detected it at 576ns. This was on a loudspeaker system. Worst case say it was theoretically detectable at 577ns say they just missed it by 1ns. That gives us a range of ability of 1 to ~16.
In expt 2 a range of 2 microseconds to 500ns i.e a range of 1 to 4 in terms of detection ability, none detected it at 250ns. Worst case say it was actually detectable at 251ns and they just missed this by 1 ns. This is a range of about 1 to ~8.
Let us say that a really bad CD player has jitter of 1ns. So for this to be a problem, detection ability on this variable has to be over 250 times better than the best result found in the paper.
Even if audiophiles are capable of far far better jitter detection (and I do not concede this point at all until it is empirically shown in blind listening tests) who will, with a straight face suggest that they are a factor of over 250 times better than the best AE, Musician or Studio professional using their own listening kit (including studios) and music they are familiar with."
As you can see, the results of that test indicate that under controlled conditions, and through competent equipment, people really cannot hear the sort of jitter levels you are likely to get from anything used in a home hifi. I'm not interested in hosting anyone who would like to try to prove to me they can hear transport differences, life is short and I've wasted too much of mine obsessing over real and imagined differences in hifi components. I don't mind occasionaly reading about them though for entertainment purposes. :twisted:
Says it all.
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