My Sony player had some setting in it to enable the multichannel output vs. the default 2 channel output. And be sure the source material is multichannel as there are some 2.0 channel SACDs out there. The DSOTM is definitely a 5.1 MCH SACD however.
Hopefully its just a setting in your player to enable the SACD multichannel out. Since SACDs are backward compatible with standard CD players, there is a 2 channel only version on them, and the players may default to 2 channel only for those that don't hook the multichannel cables up.
Best of luck.
