How can you not have multichannel system

Of course it's all about the mix, and that includes stereo. No doubt there are silly multichannel discs just as there are bad stereo ones. There are plenty of multichannel discs that do not put performers in the rear.

And Mrtennis...If you seek realism, spatial cues are quite important, and more difficult to achieve than pitch, timbre and harmonics. In fact, as your hearing deteriorates with age, as yours will too, (sorry about that) you will find that spatial awareness is affected very little, and therefore becomes even more important.

Here is another sacd article where the reviewer lists her favorite 2 channel and multichannel sacds. Along the way she sheds some light, but not right on the nose. Worthwile if you want to try a few discs, even if 2 channel.

Oops, here is the site
http://www.positive-feedback.com/Issue39/sacd.htm

For the technical or engineer, a schematic:
http://www.sonicstudio.com/pdf/dsd/SACD_FormatOverview.pdf