I have found a center to be a "must" even with actives. I've tried listening from many different positions in two different rooms and the results are the same; a center is required. Get the 160.

As for surrounds, I recommend the QS10s. They are linear enough right down to 40Hz at high SPLs for surround duty.

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