the se535 bass is natural, its more of a ''how its meant to be heard bass'' for instance, some songs when i listen to my se535-ltd-j it seems like the bass is lacking, then i turn on another track and the bass is more defined, heavy and deeper extension.
this is becuase the iem's are replicating how the bass was meant to be heard in the track, imo with the se535 you hear mid bass if your supposed to, you hear low low bass if your supposed to.
the bass is tight very controlled and is more quality than quantity, the bass isnt over emphasized, or synthetic sounding. some people mistake the se535 for not having bass, it imo wasnt meant to have saturated overemphasized bass.
i listen to ALOT of house,dance,trance,dubstep andthe like, and find the bass to be more than suited for those genre's now its not head shaking bass, its not supposed to be.
the se535 have lush mids, forward mids,sparkle highs,slighlty forward vocals,amazing instrument separations,detailed sound, great clarity.