When I had HT3's, the best sounding amp on them was the BAT VK-600SE.
Other good amps on the HT3's include: McCormack DNA-500, Dodd 120's, CI Audio D200's, and Moscode 401HR
In regards to the Song Towers, I have used them only in a HT setup. While they sounded good even with a Denon receiver, they have sounded their best with a Parasound A51 amp. Not quite as good as the Parasound but better than the receiver was the ATI 1605.
George