Short version if you don't want to read whole article or watching movie (which is only about part of article) - people do not hear sounds over 20kHz, but amplifiers can overlap inaudible frequencies to audible ones and produce distortions (that about 192 kHz) and because noise level of 16bit is so low that there is no reason to increase number of bits to 24 (it affects noise level - see video).
(and zipped video if you prefer to watch this on some avi player pl subtitles included) (copy of article from that was old and is no longer there I don't want to look for it so I created mirror) Out of interest, why would you say that it's not a good idea to use 192kHz?
