I'd question whether any digital cable has a signature sound that is evident in general from application to application. Jitter is the one thing that can affect sound that can be attributed to a digital cable, and even in this case the actual results will vary from setup to setup. If you hear a difference fro one digital cable to another, I'd be willing to bet it is a result of jitter. I have no idea what characteristics of a digital cable could be used to determine whether the resulting sound is warm or not. Maybe certain jitter characteristics could translate to a "warmer" sound. But if so that is a not a good thing. Jitter is a form of distortion associated with the time dimension. You always want to minimize jitter for best sound, ie get the timing of the D/A process correct, not use it to flavor the sound.