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From what I have read jitter is mainly a problem when sampling at higher rates than the recording was made with, Or upsampling and playing back at higher rates than the recording was made with. If you are playing back at the exact same bit rate and sampling specs, there is no jitter. Hence why some DAC separates have auto sensing that automatically play back at the same rates the recording was made..... to eliminate possible jitter.

As far as DAC S/n it looks like around 120 db is the average expected standard these days. Will we see 150 in the future LOL. My Asus Xonar STX uses the 1792 and this card is awesome.
 

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As far as DACs are concerned, I believe that most DACs if they are doing their job should sound very close to no difference at all. I'm not sure you will notice too much difference between Burr-Brown, Analog Devices, ESS, Wolfson, and etc. But I do believe the whole circuit design especially with op amp selection can allow manufactures to develop a "house sound." Someone mentioned jitter in this thread. As far as the DACs themselves I don't believe they play a part in jitter, but they need a constant stream of bits clocked in at a particular rate. If they don't get that stream at the correct rate, then you will get bit errors. A lot of times, Asynchronous Sample Rate Conversion (ASRC) is put in front of the DAC. This accomplishes two goals. It helps mitigate jitter problems, and it takes the typical 44.1khz/48khz sample rate to a new higher sample rate to fill in the gaps before it goes through the DAC and ultimately the opamps. Someone also mentioned clocking. Unfortunately, most of our digital transports were not designed too great. Both SPDIF and HDMI don't have audio clocking signals. Clocking in both cases are derived from the signal. In fact, SPDIF long time ago use to have jitter problems, but these days that is very uncommon with the speed of current chipsets and improvements in PLL circuits. Although, COAX would probably have better jitter properties than optical. Most people might point to high bandwidth optical data networks as an example of fast optical communications. Since I use to design data communication networks before I retired, I'm well aware of their capabilities. But it is not the same Gigabit high end optical gear and lasers used in consumer based technologies. You can get a lot more smear of the LEDs turning on and off leading to potential misreads on the receiving end. In addition, HDMI is based solely on DVI technology (video only transport), and audio unfortunately was an afterthought with the audio embedded in between video data. In fact, when using an HDMI transport it is best to use the highest video resolution because it reduces jitter and latency (read: this is because now the audio data arrives faster because the HDMI timing is based on video not audio and the audio is embedded in between the video data). The audio engineering society had a meeting to discuss some of the deficiencies of HDMI audio and jitter in particular. Here is a link to their presentation: http://www.aes-media.org/sections/uk/Conf2011/Presentation_PDFs/14 - john dawson - Audio Transport over HDMI - AES 2011.pdf For critical listening, I typically use SPDIF as my transport, but I have to admit at least on my gear I have not been able to tell much difference between HDMI and SPDIF in audio fidelity. I might just be lucky with my gear selection, but it is something to be aware of. In short, my recommendation would be to not look at DACs exclusively. For higher quality audio, just make sure they are using a high quality layout with high quality components. I have had great success with equipment that uses an ASRC, DAC, OPAMP chain to deliver the digital to analog conversion. I know the DACs get most of the attention, but you really need to evaluate the whole conversion process.
 
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