Ken, Andrew correctly pointed out the sub out gain can't be controlled with the receiver. As a result, he decided that it didn't make sense to include a sub out.

My buddies and I planned to fix the receiver gain and vary it using the Air's UI. I therefore see no reason to trap that first 30 Hz.

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated