Krell 300CD - what DAC to add on?

Hi all

I'm toying with the idea of using an outboard DAC (maybe the Chord DAC64) with my Krell KAV 300CD integrated player. Although the 300CD is no slouch on its own, I'd hope for more "air", detail, musicality, "truth of timbre" if I shelled out for a DAC. What would be the minimum "level" of DAC's that I would need to consider to get a reasonable improvement over the Krell's onboard DAC? Cost is an object here. Any thoughts/experiences you can share would be greatly appreciated.

Thanks and regards
Mick