I have the SRR60 sound reinforcement receiver installed in a large auditorium; can I add more sensors by splitting the infrared sensor input signal? If so, how far can I run the coax?

The infrared sensor input can be split to accommodate more sensors, however you must use a splitter that is DC passive and will operate between 2 and 3 MHz. Distance at this frequency is not an issue, if you use a good grade of coaxial cable.