I am a little surprised that all three of you guys could diagnose the problem without listening to the sample. Howdjadothat!!??
I did.
The recording is totally clipped and "saturated". Seems that the mics could not handle the changes in air pressure (SPL), at least, this is my point of view.
Otherwise, it could be because of bad batteries which did not supply enough power to the mics so it could not handle the required SPL (mics fail if they're not drained OK)
My suggestion is to test another time in similar conditions to assure if the failure resides on the mics, in the power supply (A3 adapter, did you check the voltage in the battery? because it may be drained out...) or in the recorder settings (line in, mic in high or low-sens ... etc...)
So my suggestion would be:
1-Test the battery (it should give you a little more than nominal voltage if battery is OK)
2-Use line-in recording
3-SET RECORDING LEVELS UNDER 0 db!
3-Test the mics in similar environment or audience conditions.
4-Give us your feedback.