The Adcom uses a Pacific Microsonics digital filter, which is the same part used in Mark Levinson CD players of that generation. So pretty good stuff. The Burr-Brown DAC is not state-of-the-art by current standards, but it ought to be more than good enough for CDs.
The only digital trick the Adcom seems to be missing is some sort of jitter control circuitry, like Benchmark Media uses. I can't predict if you'll believe you hear a difference. In the time frame the Adcom was designed I used to believe I could hear differences between CD players (and DAC units, for that matter). I'm also convinced I can hear a difference between the analog output of the Emotiva ERC-2 I use as a CD transport and the Benchmark DAC1 HDR I use as a DAC/pre-amp. Of course, with the Emotiva providing the analog output there's an extra set of analog cables and connections, and an extra amplification stage in the loop, and that's a more likely cause for any real audible difference than any digital artifact. Or, I could be imagining the differences.
The Adcom's output stage supports balanced connections, which usually means they've put more thought into the analog driver stage than usual, but I haven't examined a schematic to set if it's truly using differential circuitry, or just a converter circuit at the output.
There's also the chance of some capacitor degradation in the Adcom after 16 years, so it might not be performing exactly as new. But just a chance.
If you insist on trying something new, two options offer money-back guarantees:
1. The Emotiva ERC-2 CD player for $450 shipped. It's close to SOTA, with a true differential output stage.
2. The Benchmark DAC-1 for $995, and use the Adcom as a transport. It is truly SOTA when fed into an integrated amp like yours. If you don't need the money back guarantee you get from ordering from the manufacturer, Guitar Center runs periodic general specials that uniquely (to my knowledge) includes Benchmark Media products.
The question is: why do you think there might be an improvement to be had?