Best integrated amp for the new kef ls50's?

Hi there.

I am hearing great things about the new kef ls 50's. And I will be buying some soon.

What is the best integrated amp for the ls50's?

I like female vocals, jazz and alternative.

What is your recommendation under 1000 and over 2000?

So far I am interested in the Nad c390dd. But not sure its worth the price.