There are so many variables here it is pretty hard to tell. Here are some of the issues (many are not SACD specific but affect all comparisons between CD and higher resolution audio):
DSD is often converted to PCM in the player.
No consumer DSD direct system can apply bass management or room equalization.
Many so-called SACDs are just reformatted 44.1 CD data. Often the CD data is obtained by processing analog tape recordings.
Many SACDs are mixed differently from the CD version making comparison between layers on the same shiny disk impossible.
24bit 96k is pretty much the studio standard these days. This is often converted to DSD for SACDs.
DSD needs brickwall filtering to prevent HF IM issues in the audio spectrum.
I've reached the conclusion that there are so few pristine DSD recordings and that the difficulties with handling DSD in the reproduction chain (including the Sony encryption requirement and the contortions needed to rip SACDs) are such that it is a moot question whether or not you can here the difference.
The CD catalog is so immense, and the quality DSD catalog so tiny you are better off spending your efforts on improving CD playback. And promoting the idea that SACD is a dead end. Like I do.
With the large number of BD players in people's homes I'm hoping BD-Audio will catch on. I think then we might have a chance for better resolution audio to become more common.
To be more concise, SACD -> please dry up and blow away.