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As I have already wasted a tremendous amount of time getting headaches trying to do what I need to do in BiaB, can anyone recommend a good Windows based DAW?
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Asking for a good Windows based DAW is like asking what is the best car to purchase. You will get a number of different answers, including mine. I suggest you try demos of the various DAWs and select the one that is best for your workflow.
I use Presonus Studio One Pro 5.5. It does everything that I need in a DAW, is very easy to use, and fits my workflow perfectly.
What I do for pickup notes in BiaB I do the entire song in 4/4. I then bring the BiaB file into Studio One and work on the entire song. When I am happy with it I delete the first two beats of the first measure as well as any instruments I do not want to sound in the pickup measure. Thus I have the pickup bar as I want. Note this is only my workflow and others may/will have different workflows.
Good luck in finding a DAW and I hope this helps.
{edit} I forgot to add that it is very easy to move individual tracks and/or notes in Studio One. In BiaB's first measure let BiaB play the first two beats and start you pickup notes on beat 3 and 4, then use the procedure I mentioned above.