I picked one up of these last week, and got it hooked in to my small living room system yesterday (MacBook Pro -> USB -> R+X -> Integrated Amp -> Speaker). I've mostly been streaming Tidal from the app and playing a variety of music styles, but also watched a movie (Sonic the Hedgehog) with my kids. It is a superb DAC so far, I'm very happy with the purchase. But it is still new and I will let it sink in over time.
I've played with the various filters, and there is a noticeable difference depending on the track. I like having these options, I'll have to play with them to see which suit my ears best over time.
There are some practical quirks that I encountered...
(1) Straight out of the box and plugged in with no intervention by myself, everything was coming in at 44.1kHz and the sound quality was meh (the highs in particular seemed harsh). So I set the Audio MIDI Setup.app on my MacBook Pro to force less sophisticated apps to talk to "D90 MQA" at 768kHz/32-bit...the D90 instantly showed this change on the front panel, and everything sounded excellent thereafter (highs become smooth and manicured).
(2) Google Chrome refuses to talk to the D90 when playing content that includes audio, such as Youtube and Netflix. This problem did not occur on any other browsers, it seems to be specifically a Google Chrome bug. When I searched around the net, I found that I was not the only one who had this issue, and it may also be occurring with other Topping DACs (not just the D90). I'm happy to use other browsers, so not a really big deal for me.