Inofficial: Solid State Logic Fusion. The Mix Processor (intended for tracks and group busses) plugin has a sidechain filter on the dynamics section. The Bus Processor (intended for the mix buss and mastering duties) replaces the dynamics sidechain with a crossover and adds a Dimension control (fixed frequency low shelf filter inside of the mid/side matrix) to replace the pan knob.
Firma: Acustica Audio