DAC as an upgrade

Mapman - Many DACs these days have built in jitter reduction circuitry allowing to use anything as a transport. I use Benchmark DAC1 with sony DVD player using 75 Ohm coax. Toslink connects my TV to Benchmark and I have still have one more unused digital input left. Since Benchmark has volume control I have it connected directly to power amp. This arrangement allows me not only to listen to TV but also to DVD, play MP3 (inherent in DVD players) and eliminate preamp+ICs. If you decide to built your own coax use quality cable like Canare, keep distance to minimum and obtain 75Ohm RCA connector (standard are not). Most likely you will have RCA on one side and BNC on another.
Check also Bel Canto DACs - warmer presentation (not to my taste).

Audition the DAC(s) in your system before you purchase. You may be surprised at how little difference you hear. I don't know how old your Denon is, but many of today's CD players utilize excellent DACs. Do use a 75 Ohm digital coax cable (Stereovox XV2 is very good for the money). I would recommend including the PS Audio DL3 on your short list.

Mapman, what is your budget?

No set budget at present. All options open.

2chnlben,i

The Denon CDR1500 is only 2-3 years old and is still sold new on Amazon and other locations.