That's interesting because the supplied manual makes no mention of any of your supplied information.
But Thank You, it is greatly appreciated.
below is copied right from the RR2150 manual.


RP4: IR (infrared) In/Out Connectors (see page 22)
When your RR 2150 is hidden behind doors that prevent the remote
control from “seeing” the front panel IR sensor, you may connect an
optional, external IR sensor to this 3.5mm mini-plug. To send the IR
signal to another product in a “daisy change” configuration, connect the
IR Out jack to another product with a compatible IR system.