i own a b&k vmr-654 6x60 and b&w 601s.i had mine passive bi-amped for quite awhile and thought when i bi-amped them,the sound stage came up.i rearranged the system and didn't have cable runs long enough,so just a normal amp and cable setup,seemed like the sound stage collapsed.well,i went and bought new 'stuff' to make the bi-amp runs again.
keep in mind these are small,slightly inefficient speakers so results will vary.

my opinion:yes,i noticed a large improvement
if you did it,i'd use strictly the b&k(trim controls?) to get the final 'tweaks' on the system.

and i listen mainly to music,also

if i can get the shortcuts to work i'll put up a link 4 u