Finally got around to getting a SACD player (which also plays DVDs). I have been wanting one for a while (ever since I got Sting's "Sacred Love" CD, which has a CD and a SACD version) to see if the sound is really better. It certainly ought to be - instead of the usual left/right RCA audio connections it has six RCA connections for the SACD signal (essentially providing 5.1 channels of surround sound) and a optical cable carrying the Dolby Digital 5.1 sound when playing a DVD. The SACD also has an enormously higher sampling rate compared to normal CDs - I think it's 64 times the information a normal CD has.
As for the SACD - wow. I was absolutely floored by the quality of the sound and the improvement in the surround as a result of the five channels (I don't have a subwoofer hooked up yet, so no "point 1" right now). As for the DVD, having the optical cable gives me true 5.1 sound (actually it's saying 3/2.1 which may have something to do with not having a subwoofer hooked up) which I hadn't realized I didn't have before. Movies sound far, far better.
I also noticed a much better picture, probably because the unit is progressive scan. I think my prior player was as well, but it must not have set for it, because the picture quality is significantly better.
The amazing thing to me is that this unit (a Sony) cost about $115. Of course getting good cables to connect it costs the earth, but I still can't believe that a unit this inexpensive can sound (and look) so good. I'm looking forward to hearing more SACD discs over the holidays - Pink Floyd's "Dark Side" and some rereleased Alan Parsons Project and Sting are high on my list. Some are SACD and some are 5.1 (Dolby Digital or DTS).