Only had it for a few days now, but sure... In the past I used to have a HDV800, but I sold it in part due to it not having proper preamp XLR outputs (for desktop active monitors). Sound quality wise I didn´t have anything significant to complain about it, great product and in A/B tests at the store I preferred it to everything else they had at the time. So when this model finally added support for XLR preamp outputs it was an easy choice for me.
Haven´t had the chance to run it via balanced outputs yet, but it already sounds good single ended with my HD 600. It only gets better from here. My overall impression is that there´s nothing about it (in design or sound) that bothers me. It just works. Just like Apple stuff. Took me a long time to realize it, but in my experience that´s usually the best way to know something is good in high end audio. I´ve tried a lot of stuff during my Head-Fi.org voyage, but these days I´m no longer interested in the tinkering aspect of the hobby so I´m drawn to solutions like the HDV820 (= everything by same manufacturer*, one box solution).
It´s not cheap, but it´s great if you just want something that you know will work great with all Sennheiser headphones plus looks good/neat on the desktop. No cable mess from separate components, no need to spend money trying to match headphone amplifiers with the optimal DAC. Holds resale value well. Something you can just buy, enjoy and then forget about gear except maybe new headphones
(assuming you mainly use Sennheiser headphones)
Going to primarily pair it with the new HD 660 S (still think the HD 600/650 are much better all rounders than the HD 800 lineup). Is there something "better" out there in the separates headphone amp/DAC world? Sure most likely, but in this price range the differences are for me too minimal to fuss about.
* Preferably a large established company with deep R&D/engineering knowledge.