I feel like I need to step in here and correct some misinformation that is being passed along.

24 bit does not give you any more dynamic range than 16 bit. Dynamic range is determined by the analog side of the signal processing, not by the converted to digital format.

What 24 bit recording does do is give you a better signal to quanitization noise ratio than lower bit depths.

For every bit depth there is an additional 6 dB of SQNR. You can go off and google and wikipedia this to get the complex math but I'll try to keep it simple here.

Here's the way to think about this. Let's pretend you have a pure sine-wave at a fixed peak-to-peak voltage. Let's pretend that we take this signal and we amplify it so that the the peak-to-peak voltage is the same as the peak-to-peak voltage that the A/D converter can handle. You can quantize this into 16 bits, or 2^16 values, or one of 65,536 possible values. The sine wave will have very tiny little stairstepped voltage values into which the wave is encoded.

Now, let's take the same signal, and quantize it into a 24 bit A/D converter, which has one of 16,777,216 possible values. As a result, the stair-steps are WAY smaller with 24 bit A/D conversion than with 16 bit conversion.

The 'stair-steppy-ness' of the signal is the quantization noise. Yet another way to think about this is to think of the smallest possible signal that can be encoded, a signal so quiet that the A/D converter switches between the lowest possible value at zero and the next highest value. It switches back and forth between 0000000000000000 and 0000000000000001. When those values eventually get sent back to D/A conversion, that twitching between the two values tweaks the output D/A and generates an unintended analog output noise: Quantization noise. (For those of you that know binary formats, and the difference between signed and unsigned stuff - bear with me here, just trying to make a point)

For a 24 bit recording, if we adjust the signal down so that the switching back and forth occurs between 000000000000000000000000 and 000000000000000000000001, the lowest two values, and as it goes back to D/A the tweak is much smaller and hence the quantization noise is much smaller. In fact the quantization noise will be roughly 48 dB lower than the 16 bit quantization noise.

Note - no magic with the dynamic range occurs.

The big benefit to recording with 24 bit recording over 16 bit is that one doesn't really have to worry nearly as much about using the full dynamic range of the A/D converter in order to get a nice signal to quantization noise ratio, and the little stair steps that occur in the digitized data are peanuts in comparison to 16 bit.

In other words, you can be quite a bit less careful about it, and just get on with recording.

Bottom line, real dynamic range has nothing to do with bit depth.

Other bottom line, disk space is nearly free these days and switching from 16 to 24 bit doesn't have a hard and fast noticeable cost these days. It's not even computationally expensive any longer with software that takes advantage of multiple computing cores.

If your input A/D on your audio I/O device has 24 bit capability, switch over to it if you haven't already done so.

Back to the OP's original question....