[Anagmate]

This would probably be too hard & expensive to implement, but it seems as the most user-friendly solution: create connection protocol where both ends send all possible protocols they can work with (standard codes could probably be established) and the cable would include small chip & LED diode in both connectors - when you connect two devices, it would either light up green (both ends share at least one protocol) or red (incompatible).

For example, I plug one end into my phone and the other one into my sound card - it the phone doesn't support external sound cards, the cable would light up red - otherwise, it would flash green for few seconds, then turn the light off.

Another (maybe more practical solution) would be to implement this in both ports, but some vendors may not comply with the specification. (in the cable, you could only buy those cables that support the negotiation protocol - it would be your choice if you decide to pay a bit more for a better cable)