I've been listening to the topping D90 for some days now without upsampling to get a feel for the sound signature, I must say topping has really improved their implementation in this DAC to make it sound this good, at this price point.
The review that soundnews did is almost spot on, soundstage/layering is better than my x sabre pro while detail is comparable, this is with the USB input directly connected so the implementation there is pretty good.
I think in a day, or two I will start experimenting with both PCM, and DSD upsampling again on this DAC.
The manufacturer has also confirmed that DSD modulator bypass is used in DAC only mode so you can probably put it in your recommendations list whenever you aquire one, and listened to one for awhile. @Miska