If in fact there are any differences, I see no reason to expect them to be anything other than random and unpredictable, with little or no correlation with price, and with little or no consistency from system to system. Any sonic differences would be dependent on the type of dac (asynchronous/non-asynchronous, etc.), the length of the cable, the impedance accuracies of the computer and dac, the risetimes and falltimes of the computer output, emi/rfi sensitivity of the components in the system, ground loop susceptibility of the particular components and the particular setup, the particular computer hardware, extraneous background processes that may be running in the computer, etc. etc.
While some things in audio may cause a sonic difference, that doesn't necessarily mean that a sonic character should be attributed to them.
Regards,
-- Al