you can do this:
use a send for your sidechain key (kick?) and on the aux return put an eq to filter out the parts of the signal you don't want the compression to respond to, then put the mother ducker input. route the return to a master bus you don't use (i do this with master bus 7\8 which i don't actually have on the Mpc Live which has 6 outputs
) so the filtered kick will not be added to your real master bus output. i do this everytime but yes, an embedded eq on the mother ducker input is needed, even something simple like an hipass filter, as seen on almost every serious compressor on the planet. if they add that i would not be forced to "burn" an aux send\return for this simple task...
