I think that if you already have K3003 and if you love it already, Dita IEMs might be a better match than SE846, as SE846 is really smooth and toned down in treble, while Dita IEMs have an energetic treble.
About the bass, Dita has good amounts of bass, less in amount than ie800, but Dita's bass is extremely quick and can resolve fine details well. The impact is quite nice to my ears as well, providing nice rumble when the songs asks for it.
Dubstep and Electronic feels quite satisfying with Dita Truth, and I'm coming from IE800, so I require some bass to be satisfied
For example, testing it right now with Q5 and AMP5, the source is very slightly warm due to AMP5, with the details and texturization of Q5, listening loud to Dita
Metal music like Dope - You Spin Me Round has a nice impact and can give you the impulse to bang your head to the bass line
Gorillaz - Feel good inc - The bass notes that follow the bass guitar have that sweet bass guitar texturization, with not only the bass notes, but also the typical guitar string feeling, making the bass experience quite intriguing. The lowest notes of the sub-bass are not over-expressed but they are very quick and spot-on with their timing.
Infected Mushroom - Where do I belong - The bass at the beginning of the song has both a very nice impact, rumble, but is also quite well ready to move the listener to move his head and whole body to it (please remember, loud listening test)
Incubus - Antrigravity song (Summer Romance) - This song has a very thick and full bass line at the intro, which feels quite nice with Dita Truth, has a niuce rumble and a thick presence when it has to. The other part that intrigues me is the nice cymbal / bells / drums in the song, which bear amazing impact and presence, quite an uplifting and emotional presentation of this song.
Jason Derulo - turning the volume high, you can feel the bass notes hit deep and rumble you as the listener, but they don't go overboard at lesser volumes
The general feeling is that drums and bass guitars are extremely satisfying and excellent in detailing and naturalness, while cymbals are amazingly good in amount and energy, as well as the midrange is in detail and the soundstage
If you're coming from K3003, my honest input is that Dita Truth is a better direct upgrade, since Dita Truth has both the treble detail, midrange clarity and emotion, and more bass than K3003, while SE846 is more of a laid back and smooth IEM (I wouldn't upgrade to SE846 from ie800 or K3003 due to maybe lack of treble presence, I also find ie800's bass to be enough)
As for compared to ie800, I think that Dita Truth extracts more details from music, there's some stuff going on in Incubus - Nebula isn't there with ie800 (I know this song better than most people know the inside of their mouths).
When it comes to their bass, I'd sat that it isn't lacking in any way.