McCormack makes awesome amps IMO. I think they would drive the HT3's well, bahorn.
Big Red Machine uses 1000 watt monoblocks from Wyred4Sound to power his HT3's. That might be a little "extreme," but the price is very reasonable and he was very happy with how they performed.
I'd recommend Audio Research, Parasound Halo, Musical Fidelity, Ayre, Van Alstine (never heard it, but his gear is well loved), Plinus, Classe, Bryston, etc. Personally, I'd try out the wyreds, though, as the price is just unbeatable for the performance. My buddy warpdrv has a wyred amp and loves it, and I agree that it sounds spectacular.
Edit: I see BRM beat me to the punch. Haha.