And I third the CD-25 (also known as the Shanling CD-S100)! It's the very best player I know for the money.
I think the other guys' recommendations are excellent, if I may say so. The Audio Refinement gear is very good value IMHO. I'm only chiming in to reply to your question: how much do you divide the budget between amp / CDP / cable ?
My personal answer is, spend all you can on the source.
After all, you will be upgrading again, eventually, won't you? Getting the best source you can means you will be happier with it for longer. The next major effort can be on the amp, because you will still enjoy your source. And the quality you have upstream will be revealed when you upgrade downstream.
Compare that approach with the opposite : a downstream upgrade makes you painfully aware of an inadequate source.
If I were in your shoes, I would consider spending the whole pile on a CD-S100 Mk II, and a cable. I have a review of this player here at Audiogon. But then I have access to the Canadian sources for it ; AFAIK it is not available retail in the U.S. :-(
Canadian Shanling distributor's pageCD-S100 / 100 MkII reviewNevertheless, with all that said, moving from your Nak to a CD-25 and an amp like the Audio Refinement will still make you very happy. Tell us about it, when you get your upgrade home, if you get the chance.