My knowledge is limited on this, but what I noticed is I will have a song completely dialed in, as far as mix, and volumes. I go to render, then hit the TEST WAV button, and invariaby, the midi will be really LOUD compared to the realtracks. I delete the wav, go back in and lower the midi to like 50, max out the Real Tracks. . . Then add 10 or 15 Db in the render window, then save to wav. This is if I am going somewhere else like RB, to do a final edit. This is usually where you can use the musician's favorite line of "Fix it in the Mix". So far, it works good if you are going to another program. If you are doing it all in BIAB, sometimes I have changed numbers 2-3 times before it sounded "kinda like" I originally saved it.

Bottom line, I have maxed out to 127, and then imported to RB or whatever, and just fixed it.