Originally Posted by oqvist
Thanks This and the email you sent helps resolve some of the mystery. I am not expecting you to proove anything I just have no idea how this stuff works.
Take my Elite Pro or Essence ST. I have them sitting well away from anything and they are both shielded. If I would attach the hi face through USB it would be much closer my video card and other nasty things. If I get the boxed one I could move it further away and solve that. Al though I have up to 6 usb devices connected at one time it will share power so maybe the signal will be less then optimum anyway? I currently dedicate a separate line from my PSU to my soundcard. My Silverstone Zeus has 4 lines. I generally put some more on to it to get it operating at maximum efficiency on such devices like fans that are constant speeds.
So if I have little to no EMI/RFI and my PSU which is one of the most expensive PSUs build for stable voltages are up to the task. The benefits would mainly be perhaps even cleaner power on the hiface still?
Also this? "it operates asynchronously so it doesn't rely on the computers clock for it's timing. This is theoretically the best USB communication"... Soundcards like Elite PRo and Essence ST are they synchronous to the computer clock? The Essence ST has a jitter clock and my audio GD DAC also have some advanced anti jitter mumbo jumbo. DSP that is supposed to make the transport a bit less crucial.
Would love comments from people having one of those soundcards or the STX using coaxial or optical out that moved to the Hiface and what level of difference there are. Or if I should wait if I decide to get a dead silent net book.
There a lot of factors that can affect the performance of the transport: clock jitter, phase noise clock, power supply, ground traces, output transformer, output impedance, quality of the connectors, ...
The Elite Pro and the Essential were not build from the ground up to serve as a transport. For example they don't use true audio clocks. It means that when you are listening to 44.1 CD (or any multiple such 88.2 or 176.4), their clock has to be derived from a 48 multiple which makes things even worse.
The Esi Julia use true audio clocks (one for 44.1 multiples and one for the 48 multiples). I remember reading a user (on the m2tech thread) saying that the hiface was a pretty big improvement over the Pro PCI Esi Julia.
I would also like to see the clock phase noise of the clocks being used in those soundcards. (The hiface clocks for example are -78db at 10hz and -140db at 1khz which is relatively low). Those figures are far more important than ppm for example.
Jkeny's mods have addressed the one weakness that the hiface had: the power supply. The hiface draws its power supply from the computer: even if you put the best commercial computer power supply, it will still have much higher noise levels than the battery power supply he is using for his mod. By bypassing the 3.3 voltage regulators and "injecting" directly the very low noise battery power supply, the benefits of that battery power supply are even more appreciated. Even the best voltage regulators (regardless of the power supply) will have some kind of noise.
As for the Audio-gd DAC you are mentioning, I did my tests with a similar one (the dac19dsp) and it is defintely sensitive to the quality of the transport. Kingwa, the designer of the dac, also says that while in theory it shouldn't be affected by the quality of the transport, it is the case in practice.
I haven't listened to neither the Elite Pro nor the Essence in my system, so I can only speculate. However, my best guess given everything I know about jitter and digital design is that the Elite Pro or the Essence ST are no match for his modded hiface. The stock hiface already had better measurement than the professional PCI LynxTwo card (which is a few steps above consumer cards such as the Elite Pro and the Essence ST), so it would be highly unlikely if the modded hiface didn't outperform by a very large margin consumer PCI cards such as the Elite Pro and the Essence ST.
ps: the measurements about the hiface I am referring to are here: http://www.head-fi.org/forums/f46/us...ml#post6063226
pps: I am making my assumptions about jitter and transports, simply because a good measuring and sounding transport doesn't happen by accident as there are a lot of conditions to fulfil to do so.