Crane Song Avocet IIA Box - Expansion Unit for Surround ApplicationExpansion box for the Avocet IIA system, for upgrading your system to surround capability. 5. 1 expansion requires 2 boxes, for a total of 3 7. 1 expansion requires 3 boxes, for a total of 4 Avocet IIA is designed to solve the problems of accurate monitoring and volume control as required by workstation users, studios and mastering rooms alike. It is a stereo controller with three digital inputs, three analog inputs and a headphone system. It's