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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

Showing 10 responses by djones51

djones51
4,947 posts
 
The Peachtree DAC itx has galvanic isolated USB, you're using it now. You don't need any special cable.
djones51
4,947 posts
 
So, with galvanic isolation, cable quality (as long as it's certified usb 2.0) is not that critical?

Correct.

Why is cable quality an issue with much more expensive DAC's?

It isn't.

 
Wouldn't most newer, more expensive DAC's use galvanic isolation?
Some do.
djones51
4,947 posts
 
Let me see if I can figure this out. You're using a pretty good DAC with galvanic isolation and a basic cable and getting good sound but you read on a forum somewhere that computers generate noise and you need an expensive cable even though as you said you're not disappointed in what you have? Yes, computers can generate noise, are you hearing any noise or measured any? Digital cables either work or they don't, are you getting any sputtering in your music or a high tinny sound? 
djones51
4,947 posts
 
I've tried Kimber and didn't notice a difference of course I had my wife switch between the expensive and generic cable to eliminate bias. Try the DH Labs you mentioned.
djones51
4,947 posts
 
Some audiophile cables don't meet the USB 2 certification or haven't  bothered to get them certified. 
djones51
4,947 posts
 
Yes, electrical noise can enter the DAC but is that really relevant if the DAC has a measure of -120 SINAD from the analog output? Whatever noise came in has been reduced in the DAC to inaudible levels. It might not be perfect but it’s good enough for human hearing.
djones51
4,947 posts
 
Amps will have more distortion than DACs unless the DAC is junk and speakers more than amps so if the DAC does a decent job it's not that much of a problem in the system playback. I would say nowadays it's the least of worries. 
djones51
4,947 posts
 
Benchmark has very good application notes. I've read most of them their DACs perform very well in reducing USB noise. 
djones51
4,947 posts
 
Topping $130 DAC E30 has usb noise in at <-135db, SINAD -112db, USB distribution free range 20 -22 bits 32 tone input at 192 khz. This is attached to dirty USB off a display hub using supplied cable.

Topping D90 comes in with -120.5 SINAD using USB in from computer to XLR out generic cable. Dynamic Range is almost 21bits, 124db channel 1, 123.9db channel 2. 
djones51
4,947 posts
 
Look at the measurements on the $199 Schiit Modius. Jitter measures better on USB than coax or toslink. Nothing is perfect but DAC designers are doing a good job with USB. 
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