Looks like Russound has released some updates for their C-Series hardware. You need a Russound Support Center account to access the information/files, but it does address some important issues:
MCA-C3 2.00.02
MCA-C5 3.00.02
MDK-C5 5.00.03
The MCA-C3/C5 Controller firmware update addresses an instability issue when using RIO over IP.
The MDK-C5 firmware update addresses the issue of non-functional IR pass-through after Low Power Mode.