I don't know anything about the marketing of this cable (I assume it touted improved sound) but the
patent talks about it being a digital signal cable and is not concerned about its influence on (analog) sound. The patent characterizes the problem in the state of the art thusly: "
As digital components... have been added to otherwise conventional analog signal audio systems, the cables used for interconnecting the digital components have generally been the same type of cables used for interconnecting the analog signal components. However, the use of analog signal cables for this purpose has been found to be unsatisfactory." [my emphasis]
Its solution is "
a digital interface cable for interconnecting digital components in an audio system which is tuned to comprise a predetermined bandwidth of a typical source of audio signals in a digital format or comprises means for tuning the cable to the bandwidth of a signal source of audio signals in a digital format to which it is coupled."
Essentially, they have patented an XLR AES or coax S/PDIF cable because (presumably) only conventional analog XLR and RCA coax cables had previously been used in the digital transport application. The priority date is 1992, mind you, so I'll leave it to others here to play patent examiner and find the prior art.
Now many of you are surely wondering "there's no way something that
obvious could get patented!" Well, yes and no. The threshold of obviousness is rather subjective (lol). More importantly,
the cited prior art isn't really all that close. I.e., nothing cited dealt with the problem of interconnects for digital audio signals. There's a tendency to overestimate obviousness because everything in hindsight seems at least somewhat obvious. Moreover, it's difficult to cast your mind back to the relevant date (1992) and put yourself in the frame of mind of someone tinkering with cables and digital audio signals. What are they expected to know? What are their motivations? Sometimes, the "invention" is merely recognizing that a problem (however small or tenuous it may be) exists in the first place, despite how naturally the solution arises once the problem is identified.