X-Tube technology first came to prominence in 2005 with the launch of the world renowned Silver Anniversary XT the most highly awarded mid-range cable in the world winning the What Hi-Fi Product of the Year three years in a row. These design principles also grace the multiple award winning XT40 speaker cable and XT25. As frequency increases electrons flow more and more towards the periphery of a conductor so that if the frequency is high enough only a very thin layer (or skin) on the outside of the conductor is used. This \"skin depth\" varies for different materials at a fixed frequency and in copper it means that if a conductor has larger than 0.66 mm2 cross-sectional area not all of that area is available for an analogue music signal to use.