I just received my Explorer2 and so far my impressions are very positive.
I've yet to use it with cans (this is actually my first portable DAC/amp), but I compared it with my Audio GD Master 7 in my desktop 2.1 speaker setup (which is where I do the vast majority of my listening).
Needless to say, the E2 did not top the Master 7. I'm very partial to R2R DACs versus Delta-Sigma DACs, because I generally find R2R DACs to be more "real" and "analog" sounding, especially when it comes to things like timbre (especially cymbals and acoustic guitar) and PRAT. Unsurprisingly, the Explorer2 did not have the "realness" of sound of the M7, lacking the M7's low-end oomph, as well as the M7's clear of placement of instruments, among other traits. However, the Explorer2 was notably good in terms of width of soundstage and the general neutrality of its tone. The high end was not as tinny as most Delta-Sigma DACs I've tried, which I was pleased with, since Sigma-Delta DACs are the only fair comparison for the Explorer2 (I don't think there are any truly portable R2R DACs/amps).
So, turning to Delta-Sigma DACs, over the past year I went through a variety of sub-$1k SD DACs (including the Modi, the Uber Bifrost, the Maverick D2, and the Yulong DA8). Of those, I found the Bifrost Uber and the D2 to be the best, but none topped the Audio GD NOS1704 (which I still own) or the Master 7. (I'm also fond of a Teradak R2R NOS DAC that I still have, too.) Though I don't still own the Bifrost Uber or the D2, based on comparing the Explorer2 with the Master 7, I'm confident that it would hold its own as a DAC against the Bifrost Uber or the D2 (both of which also paled in comparison to the Audio GD DACs). Needless to say, I'm impressed with the Explorer2.
More impressions to come after I use it with headphones. I was planning to buy the Fulla and return/sell the one that I liked least, but the quality of the Explorer2 is making me wonder if I should even bother ordering the Fulla. Hopefully others will post some comparison reviews soon.