Samples are a bit raw and I think pushing 0. Dial them back. A piece like this should be dynamic, with a fairly wide range between soft and quiet parts. The actual samples used sound high quality, and the composition is good, has lots of feeling, sounds like it could be quantum leap even, but you need to spend a lot more time setting up your mixing.
Wet some of those instruments so they sound like they are in a real hall, dial back the volume on most of them, work on the levels of instruments to get them exact.
Look at your DB meter and make sure nothing is pushing 0db, and don't be afraid to have the track be a little bit quiet, as classical sounding tracks often are, and it's always better to have your track a little bit too quiet than pushing 0 in the mix, because you can always turn up the master or add a touch of modest compression, but if you go over you'll get distortion.