There is no way to "cascade" USB devices, if it this what you are asking. You can connect the outputs of the 192 via cable to the line inputs of the SL 16 (combo inputs 9-167) or to the two Stereo Aux Ins or the RCA Stereo input. The SL 16 would than feed your Central Station.
Remember that the SL 16 is 44.1 or 48 kHz only.