If you can find a copy of the Stereophile review of the Arcam CD33 it might be helpfull. They did try the Benchmark DAC with the 33 and if my recollection is correct it did some things better, some not as good. I have heard the 23 and the 33 and I think that they, though not identical, are similar. Hope this is helpfull.
ARCAM CD23 internal DAC vs. stand-alone DAC
Further to my post regarding the latest Benchmark DAC vs Bel Canto DAC - I'm wondering if it would be worth adding a modern $1000 stand-alone DAC to the CD23. A few years back the internal Ring-DAC was one of the best available and adding a separate DAC would not be an advantage. But now that DAC chip-sets have advanced (along with reclocking circuitry) to the point where, "the Benchmark sounds better than a $10K DAC available a few years ago...and is a giant killer", is this still the case? This question pertains to the older and original CD23, not the latest and greatest CD33.