I have a 410 Hydrive, and it is easily able to hold its own with a heavy hitting drummer and two guitards who are half-deaf. I set the amp dead flat for modern rock and numetal for floor shaking lows, and cut the low bass and attenuate the tweeter for classic rock tunes.
What amp are you running it with, and what part of the range is missing?
*** Edit: Crap, I'm really getting ADD. You already said you're running it with an HA5500. That should easily cut the mustard, I ran mine with a HA2500 until I picked up an LMII for easier portability. I found I did have to tweak the HA to get the sound I wanted, as it seems to be set for coloration when the EQ is set flat like so many other amplifier designs out there.