The Super Audio CD was developed jointly by Sony and
Philips as the next generation of recorded music.
The disc has two layers, the top layer identical to the standard CD format, so SACDs
can be played in normal CD players.
However, the second layer, which can only be read by special SACD players, offers
enhanced frequency and amplitude range, plus addition data which could be formated
as text, graphics and/or video.
The Simple Minds SACDs were created from the new
digital remasters. At best, they offer an enhanced stereo,
but to gain any real benefits, you'll have to purchase expensive audio hardware.
I highly recommend the DVD-Audio releases instead.