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USB cables and Galvanic Isolation

I've seen that some Dac manufacturers tout having galvanic isolated usb ports.
Does this mean that the Dac is immune to noise/jitter generated by a computer usb port connected to it?
And will a special noise isolating USB cable be required in this instance?
I've seen a lot of threads touting audiophile usb cables and at present I'm not using one.  I am using an Amazon Basics usb cable from my computer to a Peachtree DACitx.  I have been thinking of upgrading the Peachtree as it was my first external Dac which I am happy with but curious as to how much of a jump in SQ I will hear with a newer more expensive DAC. 
Although, I'm not disappointed in the sound I'm getting from the computer, after reading on-line forums that computers generate a lot of noise and mess with the sound I'm a little leary of usb audio.
nicktheknife
three_easy_payments's avatar
three_easy_payments
2,097 posts
 
@nicktheknife  Well it seems my DAC USB module may have just needed a "reset".  I have a Lampizator Atlantic TRP DAC.  In order to use the USB module you have to engage a ring button switch.  Apparently I was able to to make the high pitch noise go away simply by disengaging the ring USB module then re-engaging it.  Presto - problem solved...at least for now.

If you do a search on google there are a lot of reports of high frequency noise produced by USB connections.
coachpoconnor's avatar
coachpoconnor
380 posts
 
I have owned the DAC it and thought it nice piece of kit for the money. A Brooklyn Bridge would give you a good sounding MQA capable DAC plus streaming.
kijanki's avatar
kijanki
4,432 posts
 
nicktheknife, If you hear it without signal present, then it cannot be caused by the jitter.  Even with the signal present jitter wouldn't show as one frequency, but as added noise (lack of clarity etc).  It is alway possible that electrical noise injected into DAC by any cable becomes audible when multiple noise frequencies mix on any non-linear element (like transistor or diode) producing lower audible frequency (modulation).  This happens on analog side after D/A conversion.  Since it happens in one channel only it is likely a faulty part (like tube), but finding it might be difficult.  It is also remotely possible that right speaker cable (or speaker) is next to something that induces electrical noise into this channel only.
nicktheknife OP
194 posts
 
@kijanki 
Thanks for the info.  I think it may have been a tube because I haven't heard it since but am keeping my ears open for any further disturbance.  Mostly my computer audio has sound fine.  I've used three different usb cables.  Belkin Gold, Amazon Basics and Monolith.  I can't really make a direct comparison to the three because they are all of different lengths.  They are as follows, 3M, 2M and 1M.

antigrunge2
1,444 posts
 
See the ‘USB sucks’ thread: USB generates an unpredictable set of outcomes depending on the implementation of USB ports of the server and DAC, the quality of the cable and the DAC’s clock as well as the noise environment in the specific setup. As such, galvanic insulation at the DAC is only one requirement for decent sound quality, necessary but not sufficient
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