Someone already mentioned this, and I couldn't agree more with him/her:
The thing about DK's voice is that it isn't emotionless, it's just heavily under-acted, making it seem like it's emotionless. There's a difference.
Besides, even if it was emotionless, it really shouldn't be. I mean, this guy is pure evil, you should hear that in his voice. But you gotta be careful of overacting too... It's not easy getting it just right.
Tovi 
