If they've got any kind of dynamic gain going on so that they can capture the quietest stuff when nothing's going on but not clip everything when it's louder th

If they've got any kind of dynamic gain going on so that they can capture the quietest stuff when nothing's going on but not clip everything when it's louder then they might not be able to do that. Once it's recorded only the information they sampled will be there. So if you play something really loud that's not hearable by a human but is by the recorder and it changes the gain so that it can record it properly then it can miss anything quieter than the noise. White noise above 20kHz would be perfect for this since it would also alias down to lower frequencies with a badly designed setup.