Those are Sucobox spade to BNC adapters. They are connected to the speaker outputs of the LHC-208 to attenuate the signal so you can plug The 208 into a preamp and use it as a stand-alone DAC. It seems convoluted but it works remarkably well.
The wire is the standard Dart to Zeel Link 50 ohm BNC cable. 50ohm BNC is the preferred interconnect between DarTZeel components.