I guessed that Robert, being the 'Machinae Mouthpiece', would pipe up for these members.
However, from the stuff that I heard, the Theme From JnG seems more bass friendly for Kahl; its nice to hear him piping up from the depths throughout the song.
There's another tune (can't recall the name just now, will edit later) that has a drum n' bass interlude, but IMO its a little light.
I'll leave the other members' answers to them. But if we look at the statistics, the
chance that Kahl or Jonne will answer this ain't that high. 
right so thats gonna become one of those unsolved questions of machinae seeing as kahl and jonnes combined post count is one (but this post by kahl was very good [ bouff bass tab])