don't know why you've settled on an Emotiva processor... they have a strong track record for amplifiers, but not so much with their processors. A more mainstream AVR with good room correction would be my choice, and one that has pre-outs so you could add an external amplifier IF you feel you need one later. The Hsu's get plenty loud without one. Admittedly maybe not quite true reference level, but very close, and that is loud.
I went from Polks to Hsu's, and wouldn't go back, but speaker preference is very subjective, and you should try to listen to a pair before you commit.
And even if you do decide to add external amps, why those? the Hsu's are rated up to 250 watts, so feeding them 400 may not be the best idea, IMO. And you wouldn't benefit from the XLR connections those CV amps have. You'd actually have more expense buying converters.
If you have room, you could just use an HB-1 as a center channel... it is completely acceptable, and is preferred by many to have exact matching speakers for the front 3. I use an HC-1, but that was due completely to space constraints I had at the time. Upping it to HC-1's across the front would look cool, but probably won't improve the sound much (if at all). Again, IMO.
Subs, the VTF15's look great. I have dual VTF-3's, in a smaller room, and don't feel they are lacking. The 15's weren't available when I purchased, or I'd probably have them. Buy as much sub as you think you'll need, and can afford, the first time.
hope it helps, and wasn't too rambling,
mods, can we have a 'dislike' button ?