I don't post much on head-fi since I don't really have the time, but I read it as frequently as I can. And I found that there is a lot of misunderstanding about the effects of bit depth and sampling frequency. Even in the "24 vs 16 bit myth exploded" thread. In fact most of the info is wrong.

I am a master student in EE, and have specialized in communications. Including lots of courses in Fourier analysis. Now I work in speech processing/recognition, so I am more qualified than most people here.

I will try to explain in layman terms.

Humans can hear to about 20khz. Some, and only in their youth, can go to about 22kHz, but that's about it. Any higher frequencies that appear in the signal are insignificant. We can suppose that the signal is low passed at 22kHz prior to digitization, for our purposes.

From the Nyquistâ€“Shannon theorem, you have that if the sampling frequency is higher that 44kHz(2x), you can PERFECTLY recover the original signal. That's why the standard sampling frequency is 44.1kHz.

It should be noted, however, that the perfect recovery is only possible is you can get the exact amplitude of the samples(infinite precision or infinite bit depth). And this is clearly not possible. In practice you have finite bit depth, so you cannot perfectly recover the original signal.

So bit-depth does not only affect the dynamic range, but also the error between the recorded signal and original. Higher bit-depth=better, obviously.

Higher sampling rates don't do anything in theory. I practice, they can help with non-ideal performance of filters and DACs. For audiophiles with high performance components, 88.2/96kHz should be more than enough. Higher values are meaningless, with the introduction of high performance digital filters and delta-sigma DACs.

An ugly fact that you should know about is oversampling. It can be shown that if the noise (including non-ideal performance of components) is equally distributed, 4x sampling frequency adds 1 bit depth resolution. So 192Khz, 16bit is the same as 48kHz, 17bit. I facts most DACs do this to save cost.

If you buy a cheap 24bit DAC, most likely it's a 20bit working at 256x the advertised frequency, or even worse. Since in practice the noise is no where near equally distributed, this is a complete lie.

The conclusion, do a lot of research to make sure that the DAC is not oversampling. This means that they will have to use a 24bit circuit to advertise it as such and it will perform much better that an oversampling 24bit DACs which is not really 24bit. In theory, the price doubles with each bit depth added, since the circuit size doubles.

If the DAC is non-oversampling, don't go for high sampling rates. 44.1/48 will need (near) perfect filters and other components to get good performance, but 88.2/96 is enough. What is important now is bit-depth. Go as high as you can afford.

I am a master student in EE, and have specialized in communications. Including lots of courses in Fourier analysis. Now I work in speech processing/recognition, so I am more qualified than most people here.

I will try to explain in layman terms.

Humans can hear to about 20khz. Some, and only in their youth, can go to about 22kHz, but that's about it. Any higher frequencies that appear in the signal are insignificant. We can suppose that the signal is low passed at 22kHz prior to digitization, for our purposes.

From the Nyquistâ€“Shannon theorem, you have that if the sampling frequency is higher that 44kHz(2x), you can PERFECTLY recover the original signal. That's why the standard sampling frequency is 44.1kHz.

It should be noted, however, that the perfect recovery is only possible is you can get the exact amplitude of the samples(infinite precision or infinite bit depth). And this is clearly not possible. In practice you have finite bit depth, so you cannot perfectly recover the original signal.

So bit-depth does not only affect the dynamic range, but also the error between the recorded signal and original. Higher bit-depth=better, obviously.

Higher sampling rates don't do anything in theory. I practice, they can help with non-ideal performance of filters and DACs. For audiophiles with high performance components, 88.2/96kHz should be more than enough. Higher values are meaningless, with the introduction of high performance digital filters and delta-sigma DACs.

An ugly fact that you should know about is oversampling. It can be shown that if the noise (including non-ideal performance of components) is equally distributed, 4x sampling frequency adds 1 bit depth resolution. So 192Khz, 16bit is the same as 48kHz, 17bit. I facts most DACs do this to save cost.

If you buy a cheap 24bit DAC, most likely it's a 20bit working at 256x the advertised frequency, or even worse. Since in practice the noise is no where near equally distributed, this is a complete lie.

The conclusion, do a lot of research to make sure that the DAC is not oversampling. This means that they will have to use a 24bit circuit to advertise it as such and it will perform much better that an oversampling 24bit DACs which is not really 24bit. In theory, the price doubles with each bit depth added, since the circuit size doubles.

If the DAC is non-oversampling, don't go for high sampling rates. 44.1/48 will need (near) perfect filters and other components to get good performance, but 88.2/96 is enough. What is important now is bit-depth. Go as high as you can afford.