Yep, Tips are not an issue :( I can hear the effect at about 20-30% of my direct out of my macbook, quieter than that I cant hear much detail anyway but it does get worse as it gets louder. I really love these IEM's even with this issue but I cant live with it knowing its not something I should live with.
Just to confirm that these can go very loud without any bass distortion?
In testing managed to drive them hard enough to its physical limits (quite painful) and the mechanical limiting/distortion was not in the bass department and did not sound anything like the normal bass distortion I was hearing.
I recommend sending them back for replacement then. Also they should be able to go super loud without distorting. If anything they will distort your own hearing before they actually start distorting themselves.