Interloper wrote:I'd presume that the circuitry would not lowpass filter @ significantly less than 48Khz, as it would seem to defeat the purpose of having 96Khz sampling.
Not really. As you get close to the nyquist frequency, representation of waveforms gets very iffy. Consider a sine wave at around 20kHz and a sample rate of 44.1 kHz, that gives you around 2 samples per cycle - not a lot of detailed information in that. Push your sample frequency up to 96kHz and for that same sine wave you will have 5 samples per cycle - still not a great deal, but a lot better. So 96kHz can do "20Hz to 20kHz" audio a lot better than 44.1kHz sample rate can. But what's the point of M-audio providing a frequency response beyond 20kHz (unless they have identified a niche in the market for people that want to record bats and dog whistles).
That's not to say that it won't
work, just that it may not.
Interloper wrote:Do you know if large diaphragm condensers would be a good shot? Something like an AKG414.
I would expect that an AKG414 would roll off above 20kHz. Large diaphragm condenser microphones are capable of responding to extremely high frequencies (the moving mass is extremely low), but I would think that there would be design considerations such as rolling off the response well below the resonant frequency of the diaphragm, and avoiding picking up ultrasonic interference (such as from radio gear and lighting dimmers).
I think this is going to call for a fair bit of experimentation on your part. I'd go for trying to record a dog whistle or similar before venturing out with the bats.