Shin, put in your other center or any other speaker. How does it sound? If it sounds good, your VP180 is pooched and needs an Axiom speaker doctor.

And like others have said, you don't need an HP.

Oh...get rid of that massive toe-in on the fronts and move them into the room more if you can. Trust me. They will sound so much better.

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