Not required., HS: Add Hot Swap (standby) amplifier., S16: Add 16 switches to master panel., S32: Add 32 switches to master panel., S48: Add 48 switches to master panel., S64: Add 64 switches to master panel., S80: Add 80 switches to master panel., S96: Add 96 switches to master panel., S128: Add 128 switches to master panel., VIUV-SPT., VIUV-CMI., VIUV-SMI., VIUV-MMI., VIUV-AMP-25., VIUV-AMP-50., VIUV-AMP-100.