If you select "no sub" in your receiver, the cross-over should not matter if the receiver has been designed properly. The receiver should also set all speakers to large.

FYI in my room, the QS8s are "flat" to 75Hz and have useful output to 60Hz. I can't quite remember what my 150 can do and I don't have access to my notes right now.

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