If you have ever been in an auditorium, school gym or whatever and seen connector plates in the wall or floor with a circular connector about 1/2" in diameter with two pins and a notch so you can lock a metal plug in -- that's probably an XLR connector. Probably

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8