Nait5 + subwoofer

More an academic exercise than pending implementation; however, can one split the pre-out from a Nait5 to a subwoofer, utilizing its filter, returning the upper frequencies to the Nait5’s power amplifier to send to the mains? Mine is a Nait5/Flatcap/Stageline-N.

if the active sub has a filter, why not?

Arguably, but doesn’t the signal travel through the Flatcap?