Yeah... I wish the D1050 was getting more traction around here. I listened to a couple of Bifrost at a small headphone meet-up around 9 months ago, but I don't think either of them had the Uber upgrade. One was into an Asgard and the other was going into a Bottlehead Crack (no speed ball). Both sounded really good to me as I tested them with Shure SRH-1540 (tried at the meet) and Senn HD-700 (owned for a few months at that point, still have them and love them).
Anyways, audio memory is a really bad thing, so I am not really attempting to help the OP here with meaningful subjective data points, just passing through... What struck me about the Bifrost was how clean and tidy everything seemed, nothing in particular jumped out, and though I didn't get the sense of a tremendous sound stage or deep resolution, I was also listening through amps that I was not familiar with, so I have no basis to help drive to ground what was the Bifrost "sound" versus the contribution of the amps or headphones in this particular case. It just sounded very good overall and I knew right away that the Bifrost owners have good reason to be happy with their purchase. I still don't know what I don't know... I haven't heard any of the real high end stuff yet and I am very curious to say the least. I have heard many high end to super high end stereo systems through the 90s and up to 2010, and back then I had decided that for me, there was nothing special going on above the 2k price point for DACs. Things have certainly changed to some degree, and I have yet to get caught up on the state of the industry in this regard.
I ordered the D1050 around four months ago on blind faith... never heard it, saw a couple of good reviews and decided to take a chance. From the moment I turned it on I felt like I had made a great decision. Listening to one right now, and I love it on the Focal Studio Pro more than anything, with BeoPlay 6 and HD-700 also sounding good and, from memory, having a slightly meatier sound than I remembered coming from Bifrost. Now for me, this is comforting because that is the kind of sound signature I prefer, but again, memory sucks. I really wish I could A/B a pair myself but I am currently neck deep in a very serious DIY speaker project so funds are tight.
I have been thinking about a Bifrost Uber and a Lyr 2 as a potential upgrade for me, but I am concerned that the Bifrost would be more of a side step than a step up in this case, I don't know. I could go crazy and go for the Schiit reference stuff next year, grab an Oppo HA-1 at the end of this year, or something else. I only want to add one more rig just for grins, not because I think I am really missing anything. My goal is to have around a dozen headphones ranging from entry level to high end (with HD-700 and maybe an HE-560 being as high up as I go) and then be able to listen to them on my own little "review studio" where I go from Samsung Note 3 to Dragonfly 1.2 to NAD D1050 to ??? some final rig.
So come on guys, someone out there must have access or know somebody that can run a few comparisons for us? If not, maybe there will be a headphone meet in my neck of the woods again this fall/winter. If so, I will be sure to go and bring the D1050 along for some direct comparisons.