The SW44a is required for cascading. The DP SW34/SW34a will also work. However, there is a limit as to how many switches can be cascaded and that is way before 57 receivers is reached. Another piece of equipment that may be useful is the 4 Way Amplified DishPro Splitter, (DP-1004). They could be used to feed 4 sets of 4 cascaded switches for a total of up to 64 receivers.