I can't speak to the AR D series, but the Parasounds have always been pretty clean and warm sounding, a good match to B&W speakers IMHO.
Parasound a21 Plus or twin Audio Research D300?
I currently am running a Sota Sapphire with an a sumiko arm & sumiko blackbird, Arc SP 6 into an arc D300 driving B & W 801 series 3. I was thinking about adding a second D300 or going to the parasound which is much newer technology in spite of the D300 reputation. Your thoughts please