First of all, good review. One of the few about the SD2.
On my last trip to Taiwan, I auditioned the SD2 quite extensively alongside the ie800, SUI, FIBASS and other rather high end universals.
Yet I constantly found myself going back to the SD2 for reference. Although it doesn't have sound signature which spontaniously fully appreciate, I was struck how well the sound was executed.
It was completely spike-free and had an astonishing sense of space for an iem with such good isolation. The SD2 has incredible separation (especially for an only dual BA setup).
From all iems I tried during those 2 days, the SD2 (and the UERM) were the only ones I would like to have bought on the spot.
If I were to critisise the SD2, I would say that it lacks treble extension, sparkle and speed. I found that in some faster tracks, although evertyhing was very well seperated and clean, it lacked the attack which I would have loved to hear.
I currently use an ER4 so take that as you will.
Also the price is imo high for a dual BA, univeral iem which, although very comfortable, is not very 'pretty' to look at.
I am quite sure that I will aquire this iem at some stage, as it left me with a lasting impression (I don't say this lightly).
Definitely underrated....