Keep in mind my soundcard is good at downcoding 5.1 to 2.1/headphone mode, so I'll probably get more bass and overall soundquality than you would.
With downcoded 5.1 movies, the bass of the Eterna's is epic and even a little to epic at times, but does really provide that satisfying punch that subs produce in 5.1 setups, which was really quite surprising. The soundstage was pretty damn good for an IEM, it didnt feel like the movie was in my head, although you can always tell your listening to an IEm as everything feels like its close to you (ie, effects voice, etc). The midrange is prety recessed, so dialogue is hard to hear although a little eqing in the midrange frequences really fixes it up. Overall, their pretty great IEM solution for watching movies.
Keep in mind if you dont have a great soundcard, they wont sound nearly as good. MOst software downcoding of 5.1 movies tends to lose the low frequency effects and the dialogue gets more muddled.
Overall pretty good experience, although I have full sized phones which would be quite a bit better so I digress.