I read about Super Audio CD's feautures and it says it can hold 6 times the data of an ordinary Audio CD. But I didn't understand if this is due to the SACD material (higher capacity) or to audio compression (like mini disk).
If it's the first, then SACD can't be ripped...?

SACD uses a DVD as a base disc to achieve a capacity of 4.7GB. SACD also can use compression, though it is of the lossless variety, unlike the ATRAC algorithm used in MIniDisc. Music is encoded as 1-bit, 2.83Mhz DSD (direct-stream digital), not PCM. Since the format is proprietary and heavily guarded by Sony, as with ATRAC, it is not available for use in a PC setting; thus, even if one could rip an SACD (which to my knowledge is not physically possible due to some other intricacy which I cannot comment about), the resulting data would be unusable (not to mention that it is encrypted on top of this all).

Well, I found some site that gave a glimpse about how DSD works. Won't there prolly be similar formats soon, as alternative to PCM?