If you have something on the front end to control volume then QSys or BSS BLU or similar does seem compelling.
With the QSys ability to make custom remotes, I find I don't need any front end volume control from sources.
Well, better said, I find don't even want front end volume control. Because more optimal gain staging has source input signals run at full strength through the the processors functions/filters, and then apply need volume attenuation last step, just prior to amplifier gain. Improves SNR for low level listening.
With QSys an optional license called a UCI (User Control Interface) is needed to make the remotes, which can be put on IOS devices or PC screens.
I assume the others ...BSS, Biamp, Symmetrix, etc...all offer similar remote building capability. But dunno...they may require proprietary touch screens etc)
It's really cool to be able to put
any and as many control element into the remote, and also make virtually unlimited preset buttons.
My remotes can get overly large Lol.