I turn it all the way up to 150Hz and let the receiver handle the crossover.

With the 800v4, all I did was set it once and forget it. The only thing I twiddle with is the 'nad tickler/gut punch switch. 'nad tickler for movies and gut punch for music. But even without that switch, the 800v4 is so excellent.

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