Literally just bought the HRT MSII+ 5 minutes before I saw your post. I didn't read up much on the Explorer, hopefully I made the right choice.
MSII+ is a great sounding DAC, but it somehow crashes my computer every time I try to use it for anything other than listening to music through foobar and ASIO. Not sure if there's something wrong with my unit or with the computer settings. Don't have any such problems with Modi or uDAC2, so I'm suspecting there's something wrong with the HRT.