I've generally steered clear of this "debate" over the years because inevitably, these discussions with friends or forum threads on-line almost never really "go" anywhere... Nobody leaves the discussion having really learned anything, and ultimately if the discussion turns into an argument, everyone just ends up feeling "pissed off".
The conclusion one usually can get agreement on is that the best cable is no cable. Cables are passive "components", and ideally should transmit signal without loss, and does not impart any kind of signature on the quality of the signal. This certainly makes sense especially in the analogue domain where noise can easily creep in, causing various distortions or raising the noise floor. But what of digital cables? When something as ubiquitous as a generic USB cable can easily transmit >20MB/sec data to a USB hard drive, how problematic can it be to get 150KB/sec across for 16/44, ~500KB/sec for 24/96 audio, or 'just' ~1.12MB/sec for 24/192 high-resolution audio!?
After all these months of testing and posting on various topics, I figure it's at least reasonable to explore the cable issue as best I can with (admittedly) the limited selection of choices I have available around here.
For the record, up to this point in time, the most expensive USB cable I have tried has been the AudioQuest Carbon (~$160 for 5') more than a year ago connected between the PC and a Benchmark DAC1 USB. I have since sold off both items. I could not clearly hear a difference with the AQ Carbon, but then again since the DAC1 uses ASRC, I really wasn't expecting much either. Since then, I've been satisfied with the selection of generic cables I've collected over the years as computer parts or 'freebies'. It is in this light that I selected among my assortment, 3 A/B USB 2.0 cables to test out:
USB Cable A:
- 3 feet long
- not gold plated
- ferrite core on the B end
USB Cable B:
- 5 feet long
- gold plated A & B ends
- no ferrite core
USB Cable C:
- 17-feet long! (6 feet Logitech extender, 5 feet Linksys extender, 6 feet generic cable)
- not gold plated
- possible ferrite core on the extender connections?
As you can see, Cable C was made by Dr. Frankenstein. It's unreasonably long (USB specs indicate a reasonable limit at ~16'), has 2 detachable connections in between, is not even gold plated, and who knows what kind of shielding is in that thing. Furthermore, the Logitech extender portion has the thinnest wire of all the cables. Any card-carrying "audiophile" would be laughed out of town for even suggesting they use something like this!
I. Cables tested with Asynchronous USB 2.0 CM6631A interface:
II. Cables tested with Adaptive Isochronous USB 1 AUNE X1 interface:
III. Cables tested with TEAC UD-501 Asynchronous USB 2.0 DAC: (2013-06-18 Update)For the sake of completeness, I decided to run these same "cables" through to the direct asynchronous USB 2.0 interface of the TEAC UD-501 DAC to see if we can see any differences. Some folks asked if I could try a "name brand" cable for point of reference... Suggestions included the AudioQuest Diamond, maybe some Crystal Cables... Well, I search high and low... And here's the Belkin Gold 6-ft (1.8m) which I managed to get on sale for <$10 locally :-)
That red stuff is just some electrical tape I put on it for identification on another project.
Here's the RightMark data for 24/96:
Dunn Jitter Tests (16-bit & 24-bit tests):
Belkin Gold (6'):
Cable A (3'):
No evidence of significant jitter differences between the Belkin Gold or any of the other cables including that terrible looking Cable C (17-footer).