Nyquist applies only to continuous waves, so intermittent (music) 22kHz signal would have sidebands that may encroach on the 1/2 sampling frequency limit. It is remotely possible, but amplitudes of folded signals will be extremely small (as are 22kHz harmonics). 96kHz sampling would fix it for sure, but some people claim they need 192kHz. Same goes for number of bits. 16 bits means about 96dB dynamic range requiring 96dB of system total S/N to hear it. 24dB provides about 144dB dynamic range. In order to hear lowest bits you need 144dB S/N. Nobody has that, but you want 32 bits (192dB), claiming it sounds better?
On one hand it is insanity, but on the other - if it helps (placebo effect) it helps, and there is nothing wrong with it. ;)
Other than injected noise (computer cable is connected) asyn USB should be better, since it delivers only data (timing is not involved). S/Pdif has timing encoded with data and that can produce timing jitter (DAC clock is based on it). There are many factors involved in selecting best interface (Ethernet, USB, Toslink, Coax) and nobody can know for sure what is the best solution in your home. Trying at home and comparing seems to be the best course of action.
On one hand it is insanity, but on the other - if it helps (placebo effect) it helps, and there is nothing wrong with it. ;)
Other than injected noise (computer cable is connected) asyn USB should be better, since it delivers only data (timing is not involved). S/Pdif has timing encoded with data and that can produce timing jitter (DAC clock is based on it). There are many factors involved in selecting best interface (Ethernet, USB, Toslink, Coax) and nobody can know for sure what is the best solution in your home. Trying at home and comparing seems to be the best course of action.