Well the DL200 has more power, a newer 3rd generation xmos chip, newer ESS Sabre chip with new enhancements, (and wait for it)...it has better SINAD... I think those warrant consideration, but the numbers don't always tell the whole story, and newer isn't always better.
The DX3 Pro+ has a more treble forward sound, it grated on me a lot on my old classic rock and 80's metal tracks. I would get fatigued quickly and not want to listen to music as long as I would like to. I don't have that same experience with the DL200. I listen to it all the time cause my music sounds so much better through it, better than I ever heard it before. I can finally get lost in listening to my music, instead of trying to fix what I don't like. I now find myself listening to music late into the night, and searching out new music to listen to. I never had that experience with the Topping. I think there's validity to practical experience helping to interpret the numbers, if not it seems most would just chase best SINAD ratings and call it a day. (Yes I know SINAD alone isn't the only test to look at, but it seems to hold a lot of weight around here).
I've been along time lurker on here, and have read a lot of Amirs reviews and really appreciate all he does. I get tired of hearing the all amps sound the same, and all DAC sound the same argument. I don't think Amir would agree with you on that.