I just got the E4 a few days ago and the tri-flange tips work best, soundwise for me. I had a very difficult time getting used to those type of tips when I first started using them with my first canalphone, the ER-6i, but now I find them the most comfortable and the best sound wise. On the E4 the sound fills out very nicely, and the recessed bass gains some extra oomph. It also smooths out the highs, which, strangely enough, I initially found to be more shrill and grating then on the ER-4P.