I dunno if I'm just Mr Average, but I have absolutely zero problem with the stock double silicones. I've tried different combinations of foam, hybrids, spacers here, spacers there, standing on one leg and pointing North, but ultimately I'm constantly drawn back to those little white things that came in the box. Wearing over the ear, fit and isolation are perfect for my ears, comfort is such a non-issue its laughable, and the sound is simply phenomenal.
Listening to 'Brother' by The Black Keys this morning, I was struck by just how brilliantly deep and impactful the bass reverb is with these phones, not to mention the all-absorbing sense of space and 3-dimensionality.
For me, SM3 is the perfect universal iem. I owe Audiosonic a pint for making them, and all you wonderful geeks and freaks in here for promoting them. Ta very much like.