A cable assembly for use in a hydrocarbon well of extensive depth. The cable assembly may be effectively employed at well depths of over 30,000 feet. Indeed, embodiments of the assembly may be effectively employed at depths of over 50,000 feet while powering and directing downhole equipment at a downhole end thereof. The assembly may be made up of a comparatively high break strength uphole cable portion coupled to a lighter downhole cable portion. This configuration helps to ensure the structural integrity of the assembly in light of its own load when disposed in a well to such extensive depths. Additionally, the assembly may be employed at such depths with an intervening connector sub having a signal amplification mechanism incorporated therein to alleviate concern over telemetry between the surface of the oilfield and the downhole equipment.