The Loopback from ALVA is a D-Sub25 AES/EBU In/Out loopback adapter for the RME ADI-6432. The adapter is designed to loop the AES/EBU output signals on 25-pin D-Sub connectors of the RME ADI-6432 to the AES/EBU inputs of the same connector.
This way the MADI input channels of the RME ADI-6432 can be "routed" to corresponding MADI output channels.