A quick visit to the Definitive Technologies website shows they list this speaker as 30 Hz to 30 KHz. They are not going to reach 20 Hz.
Further, since they are not listing this as a +- 3db rating, one can reasonably assume that 30 Hz will be closer to the -9 db point. For bass, this puts them in the same range as the M80.

For music, this is just fine. For movies, you need a sub.
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Fred

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Blujays1: Spending Fred's money one bottle at a time, no two... Oh crap!