Multiple IPads

If there would be a suggestion that would be it. Maybe audiobus communications between iPads maybe connection through a router or USB I/O to create the most portable future forward setup ever made available.

-2 to 4 iPads
-1 mixer or even and iPad for a mixer
-1 I/O for audio output

If I understand you correctly, this can already be done.

Juicy M - 4 iPad Mix
https://youtu.be/wMw2fXWRooY