It doesn't make sense that it is unmastered. We want to test the difference of a properly made 24 bit output downsampled to 16 bit and the original. There is d

It doesn't make sense that it is unmastered. We want to test the difference of a properly made 24 bit output downsampled to 16 bit and the original. There is difference between 16, 24, and 32 bit recordings, but it just so happens that 16 bits are enough to give an effective 120dB dynamic range, if you use proper dithering. If you do not want to use dithering "because it's not pure", you still have 96dB of dynamic range. So with dithering 16 bit allow you to represent a mosquito and a jackhammer in the same room. And even without (and that isn't a good idea, as the noise now consist of harmonic distortion which is a lot easier to hear than dithered noise) I really doubt anyone can tell the difference, 96dB is still quite a bit.