The SC-2.1X is a 2 channel 2-way active crossover unit customised for the PSS and Active Series professional loudspeakers. It accepts stereo balanced inputs, with links, and, provides full range balanced outputs for the mid-high frequencies (stereo). It also features a balanced subwoofer output - a summed and filtered output derived from both channels. For each channel there is a level control; for the subwoofer channel, additionally, a variable frequency control, and a phase switch.

While the SC 2.1 X is essentially an active crossover, it also has in-built custom equalization for the PSS and Active. Thus, its presence in the signal path is recommended for optimal performance of these loudspeakers.