Question

Cascading over AVB and use multiply Rackmixers oder Stageboxes. So you can use Input 1 of Stagebox 1 and Input 7 of Stagebox 2. Or use two 32R as 64 Inputs.

Answer 1

Cascading won't be happening for Series III mixers. You can use multiple rack mixers with the 64S but not in a cascaded fashion where the 2 rack mixers could act as a single monitor mixer, for example.