(If you can't beat 'em...
)
Mark is incorrect.
Tommy has a 5.1 audio track on the SACD layer. Well, given the reviews on Amazon and the fact that your copy says that it has it. Because it has both a stereo SACD layer and 5.1 SACD layer, you may need to toggle between them.
There are stereo-only SACDs, though. The number of audio channels should be in the description of the product, so that's how you find out.
Where you bought the discs shouldn't matter. I'll take a look at the manual for your player and see if anything catches my attention.
EDIT: Mark might have checked out the Japanese version of the
Tommy SACD, which is stereo.