New QC user here.
It would be ideal to be able to add any sort of EQ to the headphone output.
For live settings I am using the unit exclusively with inner ears - plugged directly out of the headphones output of the QC. So many of the factory presets sound great through my studio monitors, but most translate a bit harsh through my Shure inner ears. It would be great to be able to dip out some of the harsher frequencies arriving at my ears without effecting the tone going to the front of house speakers. Apparently this is possible on some other brand modellers already.