The HU is fine, altough it wouldn't be my choice.
Perfects are nice subs, but you can get more for your money with some of the "no-name subs" like Shivas or Blueprints. Try a search, there's about a bazillion posts about subs.
I'd definately ditch the Xplod amp. Here's a good deal on a very nice class D mono sub amp that would be great for driving a single 4ohm DVC sub.
US Acoustics USX-800D
