Need help - upgrade amp or pre-amp?

See my system link for information on my gear. I would like more detail and separation in complex musical pieces. My system sounds a little smeared when playing the more complicated parts of tracks from Explosions in the Sky and Beethoven's 9th, for example. I figure either the pre or the amp is responsible.
Possible pre upgrades: McCormack RLD-1, ??? (Must have remote)
Possible amp upgrades: odyssey stratos, parasound a-21, ???
Thanks in advance.