For the most part, I think it sounds good like it is.
It is difficult to be critical of someone else's tone because tone is, in general, very subjective. However, since you have asked for constructive criticism, the only thing I would suggest is that I'd like to hear it a little warmer. It seems very tight/crisp and, while they may be what you're going for, I think with your style of music that a bit of warmth/fatness may add something well-fitting to the song.
The bass in this song is the a good example of what I'm talking about
:
http://youtube.com/watch?v=W9XfryoSnIw
But, again, there is nothing wrong with it the way that you have it. I think you sound good and I envy you the position of fussing over minutia as you lay down tracks in the studio.