There's a SUPERB article in Sound and Vision written by David Ranada about why NOBODY has yet proven not only that either DVD-Audio or SACD are superior to one another, but that EITHER is (AUDIBLY) superior to regular 16 bit 44.1khz. In the article, they cite tests which PROVE that there IS audible difference between sound heard which contains "ultrasonic" frequencies (above 20khz, where DVD-Audio and SACD succeed, but cd fails). The test also proves that the differences heard were INTERMODULATION and HARMONIC distortion WITHIN the "audio band" (below 20khz) caused by the ultra-sonic content "beating against" frequencies below 20khz. In other words, (and this is something I've suggested and suspected before) when people hear "big differences" the nature of the difference is that systems which reproduce lots of energy above 20khz are generating LOTS of distortion products below 20khz, and it's the distortion products which we hear, and which cause some to declare that there's "much more detail, and air". When a crossover was introduced so that the frequencies below 20khz, and those above are being reproduced by separate drivers, the distortion disappears, and along with it the "enormous differences"!