I did wind up picking up the D5 from Amazon. bwcgrx's experience gives me a little pause but it's encouraging to hear that others have been using without trouble.
As a neophyte I'm afraid I don't have a lot to add in terms of critique other than to say that it sounds very nice indeed, as others have reported. But as I say, I don't have too much to compare it to. I have a Dragonfly Red that I use with my PC, which also sounds perfectly good but is no match for the D5, I should think.
I have the D5 connected via coax to a Bluesound Node 2i (itself having ethernet connection to modem). Listening mostly to Qobuz. Can't seem to get higher than 96KHz on the hi-res albums, though that sounds good. Also listening to my own FLAC files from ripped CDs (those all 44 KHz of course).
Sounds great with my Senn 660S, and even better with my LCD-Xs.
Sorry, "sounds great!" isn't much of a review -- but it's sincere! : )