Suggestions - New DAC for Nu-Vista CD

Hi, folks. I'm thinking of incorporating a DAC between my Musical Fidelity Nu-Vista CD and BAT VK-3i preamp. The Nu-Vista uses a PCM 1738 DAC which, I believe, is somewhat dated at this point as it doesn't have 192kHz capability. Any suggestions in the $500-$600 range? Will a separate DAC make an appreciable difference?

Thanks for your assistance.