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Open source has nothing to do with the right to contribute upstream. It's about you being able to use the software how you like and make changes to it and redistribute it.
Unless you also have a pretty decent monitoring system the group delay of the speakers isn't going to be consistent so the filters before them wouldn't matter all that much...
Even in that case I would have a hard time believing that any human in a blind test would be able to perceive a group delay of even 360deg above 2k...
You are talking about sub milliseconds differces in the time frequency content arrives at the ears, just tiling your head slightly will have a greater impact...