Soundcraft SiO-BLU Link Si Option CardBLU link Card The BLU link card can send and receive 32 channels onto a BLU link bus. It interfaces with the dbx PMC16 Personal Monitor Controller, and BSS Soundweb devices which have BLU link ports. BLU Link is a low latency, fault tolerant digital audio bus of 256 channels, which uses standard CAT5e cabling to give a distance of 100m between compatible BLU Link enabled devices. Works with all Soundcraft Si mixers, including the Expression series 32