The dynamic is probably responsible for helping in the lows... and the smoothing out of the top end is probably due to the notable recess in the highs. Sound like a good result though - glad you are pleased with them. Given the end of the cheaper UE900s, these seem to be a good low cost alternative! Yay for KZ.
Talking of dynamics, really looking forward to hearing the new UE live piece... it seems to be that the adding of a dynamic seems to be the on trend thing. Funny - people seem to be taking note now... but Unique Melody were doing it way back with the Merlin (2 high, 2 mid, 1 low (dynamic))
In other news, my Roxannes have gone to JH for an overhaul, the RHS seems to have become recessed in the highs... and it doesn't seem to be a wax buildup... so we shall see. Mind you, they have had a lot of use. Not looking forward to the bill though