Split cable CFY KPP is a popular tool to lead, for example, 2 mono signals from an interface to an in-ear monitor.  It features about 15 cm long splits at each cable end. The cables are color coded (red/black) directly at the two mono plugs to facilitate the distinction between right and left. The hand soldered plugs, 1x 6.3 mm stereo jack socket to 2x 6.3 mm mono jack plugs come from REAN made by Neutrik. The hand-made plugs are gold plated to protect against corrosion and the cable cross-section is 2x 0.22mm².