Jitter issues with dacs....

Depends..............
If you have a'good' system, a good ear, and try to use a DAC with a lot of jitter, you will be annoyed.
If you have a $500.00 desktop system... jitter is not one of your problems.
Then some 'training' to actually hear what jitter sounds like must take place, and lastly, it would have to annoy you.
Jitter is just another layer of warm fuzzy between you and the music.
If your other fuzzies are bigger, you will never, ever notice the little added fuzzy of the jitter.
As a ballpark dollar amount where you might be able to hear jitter (OK, no flames or sarcastic quips) I would say a (no LP) 2 channel system that cost $2,000. or more... you could hear jitter if you looked for it.
So basically: It IS a problem to those who find it to be a problem. If you cannot figure what it is, then don't worry about it.

From my job experience with digital electronics I have assumed that the data read in from the disc would go into a buffer memory, and be "clocked out" with precise timing. Parts-per-million would be easy (inexpensive)to do. It would not matter how irregular was the timing of data input from the disc.

I gather that most, if not all, disc players fail to mechanize this approach, and are therefore subject to "jitter" problems. Perhaps this is understandable for a $100 item of equipment, but at high end prices it is inexcusable.

I've been listening to several DACs and CD players over the last year. I enjoyed listening to those with 24/192 upsamlers the most. I attributed this preference to the upsampling.

Well, I tried a Benchmark DAC1, which has no upsampling at all and it had the same characteristics that I liked in the upsampling DACs. After a bit of review, I realized that all the DACs and players I tried (including the Benchmark) had special low-jitter circuits or third party add on clocks to reduce the jitter (in addition to the upsampling).

At this point, it appears that the low jitter was providing a benefit that I completely mis-identified as the "upsampler" effect. I don't know that I can "hear" jitter, but I can identify when it is not there.

-Rick

According to Benchmark Media several months ago, the DAC 1 upsamples to 24/110 via Analog Devices AD1896. They planned to increase the frequency to 192kHz once they were satisfied with the sound. The unit I received two months ago was marked as a 24/192 DAC.

Of course, their claim to fame is immunity to jitter. I'm using the coaxial input with DH Lab's D-75 RCA to BNC interconnect. In any event, the sound is absolutely transparent.

Jitter is a problem with virtually all Transports, particularly stock. Jitter is also increased with lossy S/PDIF cabling. It is aggravated by systems that are not properly impedance matched as well.

I can only speak for myself - I can plainly hear the effects of jitter - they are like echoes or halos around each instrument or like high-frequency sibilance. Adding a Superclock2 to a transport or DAC significantly reduces jitter and this change should be obvious to anyone that is not deaf.