Depending on the version of Audition you have, they took away and then brought back the Scientific filter set. Use a Parametric LowPass / HF RollOff and a High Shelf as low as 85Hz if you can. The Scientific filter is to EQ what a Brickwall Limiter setting is to Dynamics, nothing gets through.
By the way, nothing over 120Hz should be in the Sub track, but I like to keep it tight with only sub-harmonics being richly represented, so I like 85Hz. I guy with a deep voice could end up "woofing" up your sub track.
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