The 990 doesn't have any internal bass management for zone 2, but there are methods for integrating a sub even from the analog domain - for example, Paradigm's X-30 and Outlaw's ICBM both provide adjustable bass management for two or more full-range channels of analog audio (two for the X-30, six for the ICBM). In some cases, you can also simply use the crossover in the subwoofer's amp.