It had a 9-pin female connector for the breakout box.
A breakout box for this card, the MCB-10, was sold separately.
Still later, Roland would get rid of the breakout box completely and put all connectors on the back of the interface card itself.
Some include so many input and output connections that they have a breakout box, which often mounts in one of the drive bays, to house them.
I can see a large market in "breakout boxes" emerging in the coming years.
A breakout dock is conceptually a breakout box in the form of a dock.
I wound up winning (Hercules sound card, with breakout box!
Typically, a breakout box is inserted between two electrical devices to determine which signal or power interconnects are active .
Some professional audio applications use rackmount breakout boxes.
The manufacturer sometimes provides a breakout box to allow service engineers to test the unit.