Sonic differences will be very small. The main benefit of an Oppo UD205 instead of both your disc players (why have two?) would be on the video side, where you would be able to play Bluray and UHD Bluray discs for far better picture quality than just DVD. But that also presupposes that you have UHD Bluray source material (there is still not much) and a 4K screen.
Should I PURCHASE AN EXTERNAL DAC
I have been debating on whether or not to purchase an external DAC and/or update my CD/SACD equipment. Honestly I am not very knowledgeable about DAC chips and I am in need of advice. Currently I have the Pioneer DV-47A Elite for my SACD's and a Rotel RCD 990 for my CD's. All being feed thru my Marantz AV8802A pre amp. When I purchased the Pioneer and Rotel new they were considered very good equipment and had the better DAC chips at the time. I am using the DAC chip set in the Marantz for my Rotel and the DAC chip set in the Pioneer for SACD. I am considering the Oppo 205 if i decide to update, for SACD and CD's and Blue ray, (I also do home theater). Will the chip set in the Oppo or an external DAC be superior and noticeably different than my current equipment? How does it compare to the DAC in my Marantz? My budget is about $1000 for an external DAC. I am open to suggestions for equipment and any advice. I also use my computer to stream music from Amazon and Spotify (no Tidal or Roon streaming yet). thanks