Originally SACD assumed 5 full range speakers. Later the SACD proponents came to their senses and realized virtually all their customer base had 5.1 equipment with subwoofers, hence required bass management.

However the content producers prohibited digital SACD output, so your receiver's digital bass management won't work. You have two options:

(1) Get a SACD player with bass management
(2) Get an Outlaw ICBM http://www.gspr.com/outlaw/icbm.html