Tom helped to unscramble my slightly confused logic project in a tutorial last week. With everything straight it was easier to start working with the tracks one by one. I spent some time making sure the levels for each instrument peaked in the right places, and used a compressor to narrow the dynamic range slightly to ensure the piece will play back well on less sophisticated speakers. I adjusted the automation for each instrument to enhance its phrasing, bringing tension and release to sections of the piece, trying to keep it interesting by changing the texture and feel throughout. Listening to the tracks together again I further adjusted the volumes to ensure they complimented rather than competed with each other, and all built together towards mini climaxes and subsequent periods of rest.
Initially the melody for the whole of the first half of the piece was with the bandoneon, then the second half with the piano. I changed this so that the melody interweaves before and after the halfway point, the instruments begin to call and respond to each other a little, giving the impression of a conversation. I think this really helped to bring the piece together, to make it sound as if the musicians are playing together rather than recorded one by one to a click track which was in reality the case.