S/PDIF-how different than an IC?


I posted this on "Cables" too. One has a 75 Ohm spec and one does not. One comes in pairs and one comes as a single. Both typically have RCA's though some have BNC's. How does a cable producer change the spec on what outwardly appears to be an identical cable? If you specify from a cable producer that you want an S/PDIF how do you know they are not simply selling you one half of a pair of off-the-shelf IC's? And last but not least, how does 75 Ohm change the sound one would hear from a normal IC (when carrying digital signal rather than analogue of course)?
I know this much; a very well-respected engineer with a Ph.D. in EE who designs and produces DAC's of his own says that you are free to experiment with using a normal IC with his DAC's rather than a dedicated S/PDIF.
128x128fsonicsmith
Now I have ordered a custom made 1.5M S/PDIF using the Silver Apex conductor and construction from Analysis Plus.

I have found that BNC cables with a BNC-to-RCA adapter actually perform better than a cable with only an RCA connector on the end.
You do not want to use an adaptor. Make a cable with a BNC on one side and an RCA on the other. RCAs used for an SPDIF cable are special. You can not use just any old RCA without killing bandwidth. You can use an SPDIF cable for an analog signal but not the other way around.
Pasternack makes an RCA connector that is very similar to the Canare.  It has the internal brass pin that is inserted into the RCA connector itself.  This is the same idea of a BNC-to-RCA adapter.  I don't know about the Canare, but the Pasternack was really crappy.  It presented a harsh/bright sound.

The best BNC-to-RCA adapter I have tested is the Black Cat BNC-to-RCA adapter.  It has the best and most transparent resolution.  The Black Cat doesn't have super grip on the plug, but it sounds better than other adapters.  The Canare adapters are soft and distorted.  Probably the next best adapters are the gold-plated cheap Monoprice type adapters.  These are the exact same adapters that Nordost includes on their cables.  The gold-plated design presents a slightly warmer sound with slightly more rolled-off highs.