Here's the lowdown:
MADI is not like word clock.
MADI uses 75 ohm coax, but is point-to-point only and does not allow daisy-chaining. Thus, it does not require any external termination — this is done internally on both transmitter and receiver ends. T-connectors should never be used.
The proper connections would be:
RME MADI out –> 75 ohm BNC cable –> H9000 MADI in.
H9000 MADI out –> 75 ohm BNC cable –> RME MADI in.