I had a chance to hear the SE version in my system against a Plinius M8 and Parasound JC 2, as well as a non-SE version in a different system compared to a Modwright 2 box, Audio Valve Eclipse, and Esoteric C-03.
In both scenarios, the STP preamp did a great job and in no way was outclassed by the other preamps (even though the other preamps cost between $4-10k each).
As others have noted, the STP's strengths include a very dark and quiet background, very good dynamics, deep bass, good transparency, and a nice set of inputs/outputs.
That being said, in my system, I found the STP not to be as engaging as the JC 2 or Plinius M8. It simply didn't pull me into the music in the same manner that the other two preamps did. It also didn't extract any more information from the music than the other two preamps.
Great value, but not quite the dragon slayer in my system.
George