There is no such "fact." As I explained in that thread, USB noise is system/condition dependent. It clearly manifested itself when I perform the review. But later did not.
FYI, I have updated the review here with the measurement from the USB cable test. I also clarified that all the measurements in this review were with Toslink so not impacted by USB noise. In other words, I gave the Hugo 2 the benefit of doubt and let it perform its best using Toslink.
Thank you for replying. Noted all.
It seems the same device in the same test rig, can at times have as much as 10db noise, and at times not, so it is a random situation, am I right?
If I am right, then wouldn't it be prudent, to include two noise tests on USB input, one with an isolator and one with deliberate noise injected, to see how the device behaves under those conditions.
Again, if I did get it right that phenomena is random, then one can not be sure, if a device being tested
got lucky on the review day!
Hugo2 is primarily a portable device, and as you correctly mention in the review, it is excellent at it. Hugo2 is single ended, and does not have isolation on USB, does any portable DAC/amp do?
Can any single ended DAC without isolation on USB, combat ground loop noise, if it gets
unlucky and be exposed to a large noise?
I suppose, Chord could be more clear about that and suggest the use of a USB isolator, if being used with two grounded external devices. Or, simply use optical.
Also the 1kHz sidebands on jitter test look curious, what could cause that? exactly 1kHz! anything on USB architecture with a 1 kHz .... whatever?
Also, for clarity, do you think it is prudent to show that the Audioquest cable, is also ineffective in a
noisy situation?
If it can be shown, when noise does exist using a generic cable and then no changes with another cable, the point is clearly made.
Personally I doubt you would get a different outcome, but I felt that before you even tested it, however, the point was to discover, one way or another.
As I said in a previous post, if one does not have a headache, he can not claim ibuprofen is snake-oil, because it cures nothing!