This really is promising! I had the feeling that even though the DX100 has a very, very good reputation SQ wise, the HM-901 would be a step up. Or else HiFiMan had a problem with their asking price and what it offers compared to the iBasso. I also prefer the SDXC format to microSD. I would however have preferred a much larger onboard memory. 8GB is not much, when you feed it with lossless and high res files. That's my only complaint so far without having had it in my hands.
I totally trust Tupac's judgment, but I will wait a bit before being sure the 901 is a "step up" vs. the DX100. I am not saying that because I own the DX100. I will try the 901 as soon as I can here in China, but I think we need more time with the various cards, synergy with various iems / cans, various tastes, etc. before knowing to what extent this DAP bring something significant to the game.