Sorry if I missed this but do the Senns not require burn in? They are a dynamic driver right?
It seems in previous Senn offerings 60% of the posts were about burn in and sound changing/improving. I haven't read everything about IE800 but I have seen little to nothing about burn in.
The Sennheiser IE800 happens to be the only IEM with a dynamic driver as of now, I believe. Also, I don't know if it's a placebo effect or not, but I did a burn-in of about 12 hours and the sound quality seemed slightly more dynamic. I really don't know if it was just me, but if it is, it could be that the IE800 doesn't require burn-in, and that it's just a placebo effect. However, I think I did notice a slight difference in sound quality after a 12 hour burn-in period.
But like I said, the IE800 could either have better sound after a burn-in period, or it could just be a placebo effect. Who knows....