I don't have a SMD unit, but I do have 4 "different" DS-2 and the early versions (MIJ and early MIT) are smoother then those that came after (not by much, as usual).
The reason for that are the Ge diodes (D14 and D15) and, my opinion here, those orange film capacitors that Boss used by the end of the japanese and beguining of taiwanese manufacturing.
Later on, Boss swapped to silicon clipping diodes, and the distortion became just a tiny bit more "granulated".
About those orange film capacitors, they are also in the OD-1, DS-1 and SD-1 of the same era, and comparing them with units with the same chip and same clipping diodes, but with the "regular" green capacitors, one can hear that somehow they "feel" smoother.
My DS-2 family have a MIJ 1988 just like yours, an early MIT 1990 still with Ge diodes but with red film capacitors, a later MIT 1999 with silicon diodes and silver caps and a recent MIT 2018 with silicon diodes and white (milky) caps.
They all sound great, but the old ones with Ge are the champions.
Take care of yours because it is the best incarnation of this model.
