Loomisjohnson - Only you can decide that. Benefit of upsampling DACs lies in jitter rejection and not conversion frequency. For instance if you deliver 24/192 signal to Benchmark DAC1, it will output it to 24 bit DAC at 110kHz (going in the process thru 1 million times oversampling). In that case it is really downsampling from input to output. It is because DAC chips have much lower distortion at about 100kHz than 192kHz. Whole thing is utterly complicated and I would not try to understand it but to listen first. Benchmark (and possibly others) have 30 days free evaluation program. Many people have issue not with upsampling or oversampling but with digital filtering it involves. Lately Stereophile tested Meridian CDP that used different filtering algorithm with beter pulse response and they proclaimed it the best sounding CDP so far (it better be for $16k).
Good CD players use double PLL plus output buffer to eliminate jitter but external DACs allow connecting music server, HDTV, DVD player etc. I don't know how good Denon 3939 is. My Benchmark is more better (as they say in trade) than Cambridge CD4SE (one of better Cambridge players) I had before.