The problem with synth or even pre recorded instruments is ambience control which is prebaked in the orginal sounds. Matching ambience levels is virtually impossible but a good start is to think of things in terms of room response. You've built the orchestra now build a room in which that orchestra resides. You can do this with a series of delays and reverbs. For sounds with too much ambiance you can Gate the instrument and eliminate excessive room bounce or unpleasing tails this will tend to make roomy sounding instruments drier.
Let's say the violin section, generally left as you face the orchestra has 3 bounces. One short bounce off the immediate left wall, one possibly deep back wall bounce and a medium bounce off the right wall. You can build this response with a short delay left, reverb with narrow field and long pre-delay for the middle and a medium delay to simulate the right wall. For the right side of your orchestra you would build the opposite set of another delay for quick right wall bounce, keep the same reverb for back wall and then a medium delay for the left wall. Route your instruments accordingly. For instruments in the center of the orchestra you could build another two delays l &r with a slightly longer delay because they are farther from both the left and right walls.
You can get really crazy and build an ambient response for the walls behind your head as well, all with longer delays to create a live hall approach. All of the above is just one approach. Overall film orchestras need a large virtual space but much drier sounding than your average hall so you can adjust your delays for this response. Don’t forget the ceiling too, that may need a delay or reverb depending on your required effect.
I might then take the overall dry version of the orchestra and very lightly compress it down a parallel buss to bring up lower level sounds of the orchestra and mix that back in to simulate the punch effect when the orchestra gets louder. You might want to automate this under another track for even more control.
Regarding mastering, depending on the results the above yeilds, I would probably not compress the final tracks but only limit them with some possible EQ i.e. rolling off below 40 Hz and trying to chase any rogue sounds with parametric.
post edited by Middleman - 2006/12/15 11:25:20