I only have the bluray, but I'm sure the DVD sounds great as well (if that's the only media you can use).
I hear you. It's difficult to get a really good 5-channel amp for under $1,000. Hard to get the best of both worlds (for what you want).
The Parasound A23 is a fine choice and would have the sound quality and impact you are looking for. It's okay to mix manufacturers, but keep in mind that the sonic signature is going to be different. I don't know the sound of NAD, but I have read it's warm. The Parasound is going to be slightly on the warm side, but still very detailed. You might have less resolution on the center channel if you use the NAD. Also, when sounds pan across the screen, the difference in sonic signature between left/center/right speakers could be noticeable. I don't know how critical home theater is for you.