I can see you're into Van der Graaf Generator (and possibly King Crimson). I saw VdGG live twice in London in 2005, on 6th May (yes, at the reunion after nearly 30 years) and on 8th July (the day after the London bombings). KC is my favourite band. And, BTW, I'm not into Yes or ELP, but love KC, Robert Fripp, Brian Eno, VdGG (& P Hammill solo), Henry Cow and early Genesis (& PG solo) and David Sylvian.
Now, I have the custom ES3X, which is an improved version of the universal UM3X. Some people here have stated the SM3 is an improved version of the UM3X. If that is the case, you won't go wrong getting the former. The recent 40th Anniversary KC remasters (ItCotCK, Lizard & Red) sound absolutely superb with my ES3X. And so do the 1970-1974 Genesis remasters. I have all VdGG remasters from a few years back and they all sound pretty damn fine with my ES3X. My guess is they would sound as good with the SM3 or very close to my customs. I have the Sony X 1061, no amp and mostly use 192/256 kbps aac files.