Originally Posted by moooog
I've been listening to the Pioneer in stereo on the USB-DAC, and 7.1 over HDMI. My opinion is that they are both sound outstanding, but I just prefer the HDMI with the sub. I have a rectangular 25x14 room with the mains on one end, and I have my main tower speakers bi-amped, but I just prefer the balance over HDMI. I just can't hear any significant jitter or drawbacks pver HDMI from my HTPC to the SC-68, and I hear a lot of detail and stellar imaging with either setup. In layman's terms, what is the audio improvement I should hear with the USB-DAC? Does jitter come across as sibilance? Muddiness? Noise/hiss?
Before I give my opinions I would like to say that although I prefer the sound of my Mapleshade adapter to the USB-DAC, my suspicion is that the USB-DAC is not working optimally with my setup. Whether this is due to some problem with my computer, the Pioneer driver or the USB-DAC itself I don’t know. However, Pioneer have been informed of my dissatisfaction and my case has been referred to the quality team in Japan. I am hopeful that at some point they will be able to improve things (PC driver update or firmware update?) such that I will be able to switch over to using the USB-DAC as my preferred two-channel playback device.
Just from reading the posts to this thread, clearly there are a number of very happy customers, so I am really hoping that Pioneer can help improve the sound of the USB-DAC for my setup, after all I did pay extra just to have this feature. Hopefully Pioneer will make me happy and a USB-DAC fan eventually.
Well, I can’t claim to know what ‘jitter sounds like’, however I can tell you about my listening experience of the USB-DAC, compared to my Mapleshade USB-S/PDIF adapter. I don’t know if the difference is due to jitter, some other issue with the interface, or because of a problem with the current Pioneer driver (which they are supposedly investigating at the moment – Note, this maybe XP specific, so may not affect you if you are using Win7).
With the Mapleshade the sound is more ‘precise’ and more natural sounding, characteristics which I would say contribute to this experience are:
1. Vocals (particularly or the ‘airy’ female type) sound more lifelike
2. Acoustic guitar sounds clearer, you can almost picture the musician striking the string with his finger/plectrum. You can hear the musician sliding his/her fingers across the strings as he/she switches from playing each note.
3. There is generally more sense ‘attack’, more ‘impact’, this being especially noticeable with instruments such as cymbals and steel guitars
4. Subtle sounds like drum brushes are more evident with the Mapleshade, and are almost lost with the USB-DAC.
5. When the music gets very ‘busy’, the Mapleshade is able to hold the image (soundstage?) together better
Working in the field of digital video and digital audio design I can appreciate that all the above could be attributable to jitter, although it could also be due to other issues (such as Windows mixer not being properly bypassed and therefore the stream being resampled to 48Khz). However, IF the problem is jitter then I can appreciate it contributing to these sort of sonic differences.
For best reproduction of the original digital source, an accurate extraction of the sample clock from the bitstream is critical. With the aim being to recreate as accurately as possible the original sample clock which was used to lay down the recording. Any jitter present will to some extend modify the reconstructed waveform.
Huge amounts of jitter would sound awful, but very small amounts of jitter would show up as slight inaccuracies in the edges of the reconstructed waveform. Transients would lose their ‘edge’, and this in itself could explain all the things I mentioned in 1-5 above.
I read a very good, but lengthy paper on the subject of jitter in digital audio, I posted the link earlier in this thread but I will provide it again here for your convenience:http://www.tnt-audio.com/clinica/diginterf1_e.html