Not sure if I'm understanding you correctly. QMix is a free app for IOS devices that controls various hardware mixers in the Presonus lineup via wifi. Unless the Quantum has an internal mixer (and it might for all I know) QMix wouldn't have anything to say to it.
As far as S1 goes, could you get by with an iPad running Studio One RC? That also gives you a way to have somebody in the band control the transport.
I have a 32R, so I can offer a separate mix to all the band members when recording or performing. It can become a little complicated when doing overdubs, because you have to keep track of which channels are coming back from S1 via USB and which ones are live inputs. I tend to just bring a stereo mix in from S1 with whatever people need on it and allow them to add it to their cans mixes as they prefer.