Please someone reassure me that there's some kind of internal fuse on the XLR input circuitry as I have just connected a hot line level input to channel 2 with the input switch set to "mic" by mistake. I got a (brief) full scale deflection on the audio meter then an ominous nothing.

No alteration of the gain settings makes any difference. Have I fried the input on channel 2?

XH-A1 (not the newer s model)

Well it would appear that the Canon XH-A1 has more sense than I have. Some kind of overload protection seems to have been triggered.

When I finished work today, I did methodical tests on all the audio inputs and was very pleasantly surprised that the Channel 2 input is now working again, via XLR input on mic and line levels, with and without phantom power. So I don't know what happened to cut off the excessive input signal, but I am extremely relieved that it did.