DAC vs. New CDP

I've just started looking into what DAC's really are. And I now have a question that I would like some opinions on. I've heard that DAC's can make a CDP sound great, but what if, for a few more dollars, I just got a new (or very nice used) CDP with the very latest DACs already inside?
I have a Classe .5 CDP, about seven years old. I know it doesn't have the modern DACs in it so I would think it's sound isn't as good as it could be. I'm wondering if I should look at a DAC to help the sound (CDP only has a AES/EBU output) or purchase a new or newer CDP. I've been looking at the Cambridge 840, Krell 280, Sim Audio, Bryston & Classe, all in the $1,500 to $2,000 range new or used. I know that the Benchmark DAC will cost around $1,200 new. Very few less expensive DAC's have an AES/EBU output.

My system is: Krell KAV 2250 amp, Krell KAV 280 pre, MF phone amp & headphone amp, Rega P1, Paradigm Studio 60, Kimber and RSCables.

Thanks for any input, ideas or experiences !

Jim