Sound Devices A20-SuperNexus 8-Channel Expansion License -- Purchasing one A20-SuperNexus 8-Channel Expansion License will upgrade your 16-channel A20-SuperNexus receiver to 24 channels. Purchasing a second license will bring your receiver to its maximum capacity of 32 channels. It is not possible to exceed 32 channels on a single A20-SuperNexus receiver. Device serial number required.