EXP1 is an expansion board for the MRK980 receiver that significantly extends versatility by adding Zoning functionality, Monitor Cascade, and generic GPIO interfaces. It enables cascading several MRK980s with a shared audio path and provides a GP OUT interface (two programmable outputs) via a mini-XLR 6-pin connector. External monitoring uses two mini-XLR 5-pin inputs; zoning uses three mini-XLR 3-pin inputs. Dimensions are 20 x 94 x 103 mm; weight 100 g. Requires MRK980 with EXP0, max one per receiver.