One sub shared with stereo and AVR?

Hi,

Can I share one Rythmik F 12 between my 2 channel Sansui AU-717 and a ONKYO TX-SR605 AVR?
80% music, 15% tv, 5% ht. Room is 15 X 20 home office/family. Using Ascend Sierra-1's hooked up to sansui. Using Sierra 1 center and Ascend CBM 170's for L/R, surrounds. Can I hook up AVR to sub LFE? What Sansui out (has A+B) L or R or Both would I use?
Looking to upgrade to Dennon 4311.

THANKS!!!