RCA cable has the most difficult design that all aspects of signal transmission should be considered comparing with that power cable only need to meet the square requirement and the classification of speaker cable is based on power. In addition, according to each person's different hobbies of music,RCA cable has different characteristics. As well as our cars, there is a run-in period between cables and equipment. The more superior cable is, the longer period is. So the conduction time needs several days or even one month in order to avoid impure voice and tone. The top-level cable is customized based on personal preference which is too expensive to do mass-manufacture.