Which one is perfect for music

You should probably post this question in the digital or cable forum as well.

It has been my experience that if you are looking to take advantage of a surround processor then optical is best. If you are looking for the best 2 channel music, then I say go with the RCA if that is what your player has. That said, I have found the best digital playback is when the designer keeps the entire circuit balanced from the dacs to the preamp. IMHO, YMMV

Um, you need to be a lot more specific as to the application and setting. Generally speaking though if you're referring to digital connections, an rca coaxial connection is considered better than a tosling optical one. But again I have no idea if that's what you're asking! Please provide more info!!

most audiophiles prefer rca digital to optical primarily because the majority of high end gear doesn't have optical inputs or outputs. rca digital is a more robust cable compared to optical which is more fragile and easy to damage due to the fiber optic conduit inside the cable.

rca is best.