Originally Posted by Fork
This is incorrect. USB cables do not always deliver the same performance. This conversation has been going on since 2007 and it's been well settled except with everyone who can't hear a difference with USB cables in their system or more often than not, hasn't tried.
Yeah it has been settled to be nonsense. Can you name any reference that shows evidence to the contrary, that a cheap but built-to-spec USB cable fails to transmit properly?
The USB standards were not designed with sound quality of a DAC/computer connection in mind.
Eh, one of the main goals of USB was/is: "Full support for real-time data for voice, audio, and video".
That's why we have isochronous transfers in the first place:
Constant-rate transfer: check.
Guaranteed bandwidth: check.
Bounded latency: check.
But back to cables, they don't care if you send a data packet that contains 1 ms of audio or 1 kB of text. The cables are specified to be able to transfer magnitudes of more data per second than even 192 kHz, 24 bit, 8 channel audio.
With bulk transfers you can do a simple check using a cheap and expensive cable and comparing transfer speeds to your external HDD. At least with my cables it didn't change one bit, which means the cheap (< $5) cable produces just as few errors as the expensive one because errors would mean retransmission which in turn would slow down the transfer.
Similarly, you can get crazy (~100 MB/s) transfer speeds over arguably much more complex Ethernet cables without any (nada, zero) transmission errors over several times the max length of an USB cable. That's 30 cents per meter. Why should a USB cable built to spec fail to transmit 1 MB/s over a few meters?
Connecting to a DAC is not at all like connecting to an external hard drive.
Right, an external HDD doesn't need constant-rate transfers, guaranteed bandwidth or bounded latency. It just waits for data or tries to send data.
Your sound quality through USB will depend on a number of factors, most importantly the level of resolution your components can produce, also the cable length, the audio driver and the extent to which your BIOS and OS are optimized for audio.
What level of resolution other components can produce doesn't change the sound quality of USB per se, but I see where you are coming from. Cable length is limited by the USB spec to 5m, yes. Audio drivers are supposed to be bit perfect - if not upgrade to hardware with non-broken drivers. BIOS/OS, yes since the computer needs to provide those data packets (see above) at least 1000 times a second. Any failure to do so will result in a (usually plainly audible and annoying) glitch. A broken (not built to spec) USB cable is not much different in that aspect.
If your setup isn't exactly cutting-edge, don't worry about the USB cable; from what I've used I'd say at least something like a Burson Conductor with Senn HD800. I find the Furutech to be very good for the money (we sell Furutech, so I'm not unbiased). How Furutech can make a 10M USB cable, when the standard has always been 5M max is beyond me.
If they really make 10m cables then they are not proper USB cables. Propagation delay is about 5ns per meter. The USB spec limits max delay to 26 ns. So about 5 meters max.
They only way this could work would be an active cable.
I have not found the same to be true with HDMI cables. In my experiments with a digital TV signal (analog was improved) a PS Audio silver cable did not improve the picture from the one that came in the box.
Because the eye is not as easily fooled as the ear.