A lot of audiophiles in here.
I think the difference between a CD and a higher end medium (like SACD) would be impossible for most people to spot in a blind test.
First, even for CD, most people don't have the systems needed to accurately play it back at the best possible quality. The speakers are usually the weak link, but another thing to consider is the acoustics involving how the room looks, the furniture (damping), speaker placement and last, but not least, the background noise. All these factors makes even a CD far beyond the needs for 99.9% of people.
Sure, with a really high end system, possibly with great headphones in the above $300-range to shut the background noise out, then you maybe could see some very minor differences to some parts in some cases.
But I doubt it.
I have a quite high end system where I have done A/B-listening with a pair of Senheisser HD-600 headphones comparing a mix in cubase with 96 Khz vs 44.1 Khz (with 24 bit), but I couldn't spot any difference. Even when really forcing different types of sound.
Same thing in Audiophiles forums where they miss blind tests between 44.1 and 96 kHz.
Here is a "Audio Myths Workshop" video on Youtube that I encourage every self-proclaimed audiophile to watch:
http
/www.youtube.com/watch?v=BYTlN6wjcvQ
Notice that they link to separate downloadable files to make your own comparisons.
After all is said and done, I think it is just another market ploy to sell new things...