I had dramatic burn-in for weeks and weeks and I thought too for a few days that I had lost my mind! How many hours do you have on them? I would recommend 400 solid hours as a minimum. I would also comment that the positioning is critical for bass especially as well as amplifier matching. I do not know Naim at all other than knowing they have a great reputation, but it is SS correct? The Superflys are designed with tube amplification in mind, unless I am mistaken as sometimes happens.
The Superflys I auditioned where not picky with positioning, the sound stage was out in front, engaging, and for lack of a better term, Intimate. They were paired with a Quad tube amp using KT-66 tubes.