Depending on how the amp’s inputs are configured. Some use XLR plugs as convenience only. The (-) pin is grounded, and therefore, it’s really just an unbalanced input, with an XLR plug. In this case, the RCA and XLR inputs will have identical impedance from + to - (which is what is being asked for).
If it’s a true balanced input, it may have 2 x the input impedance from + to -. I suggest using the current flow at 60 Hz to tell. Most meters are only good up to a few hundred Hz, if that much. See how much current 1V of input causes, and if it is cut in half on either input.
Of course, another way to tell may just be to test the impedance from pin 2 and 3 to ground with the amp off. you won't get an accurate Ohms reading, but if pin 2 or 3 are grounded, that's your tell.
Best,
E
If it’s a true balanced input, it may have 2 x the input impedance from + to -. I suggest using the current flow at 60 Hz to tell. Most meters are only good up to a few hundred Hz, if that much. See how much current 1V of input causes, and if it is cut in half on either input.
Of course, another way to tell may just be to test the impedance from pin 2 and 3 to ground with the amp off. you won't get an accurate Ohms reading, but if pin 2 or 3 are grounded, that's your tell.
Best,
E