Don't hold too much importance in measurements, they only tell a part of the story. I'm neither a subjectivist nor an objectivist - I appreciate meaningful measurements but also trust my ears.
Amir at audio science review has a hard on for Topping, he gives everything they GIVE him a glowing review and the distortion measurements are totally meaningless as they are well below the level of human hearing.
Zeos (Z Reviews) is a decent entertainer but a lousy reviewer - he also gets given a lot of Topping and SMSL (same company) gear.
Personally I would go with either the ifi Zen DAC, which sounds good, has good features, such as MQA should you wish to listen to Tidal and a very usable bass boost button. It's not the most powerful amp out there but will be plenty for the Denon D2000.
If you do want lots of power for (future) harder to drive headphones, then the Schiit stack of Modi 3 (DAC) and either Magni 3+ (amp) or Heresy (amp) can be yours for just over £200. The difference between the Magni 3+ and the Heresy is that the former uses discrete components in it's circuitry while the Heresy uses op-amps (chips). The Heresy was built to see if an amp designed and built purely to measure well could also sound good and it turned out to sound so good Schiit put it into production alongside the Magni 3+. As for which sounds best, well that's subjective as it's totally down to people's preferences but both seem to be selling well.