sound quality difference between USB cables
The digital path, as long as it is good enough to work, will not make any difference.

A long or poorly shielded USB cable can cause noise problems on the power supply side of the attached device. I have seen this on electronic test equipment using long and very thin USB cables. This has manifested itself as a 50Hz buzz on the 5V line which is then picked up by the ADC in the device. I would imagine it would be the same for any sound card.

Most cables are however fine.

The particular articles linked to sound like the usual made up audiophile rubbish though.