2 or more monitor output switch in cntrl room

would love to have a switch in the monitor button sutup which enables multi outputs to momitors at thr moment ists only A or B or C depending on what you have
mains on A sub on B secondary mons on C—
i would love to have A +B or C+B or all in mode there is hardware i know but it meas signal paths are longer etc

Yes and to be able to add more then one Phones Amp would be nice too.