I had a chance to listen to one yesterday, albeit for a short time. It has come a long way since the prototype i saw and heard a while ago, with wires dangling out of it.... I was able to put in an sd card with my tunes on it, and listen thru my iems. I was able to plow through a few minutes of each of about 6 tracks. I thought it sounded good enough to hand over my 801, as a down payment for the 901. I am told that US customers should see theirs some time in March, after the first batch passes muster with the mainland Chinese customers. Fang would rather be slow than wrong - he wants these to be as close to perfect as possible before he exports them from China. I would say that it is a nice upgrade from the 801 in terms of form factor, features, UI, and most importantly, sonics. It is not syrupy and forgiving, but is not bright or clinical either.
In fact, Fang almost left with the sample sitting on my desk. I had that brief crisis of faith where i wondered whether it would be OK to pretend that I didn't notice it was still sitting there. Luckily my strong moral sense, and that alone (the fact that i did not have the cable needed to recharge it having absolutely nothing to do with it), caused me to hand it over before they left the building.
There were also some interesting iems, one of which Fang did leave with me to sample.
The 901 will be a serious contender, and worth the asking price for those looking for top-tier sonic performance.