I found this really neat piece of software that optimises passive crossovers as long as you have ZMA and FRD files (which are pretty much a necessity anyways). You can even optimise for cost if you put your own parts lists in there for passive components! Seems pretty awesome. I’ve had a fiddle around with it, but not too much, if you have any questions feel free to ask. To install you have to extract it first. Latest version info & download (xmachina-ai.blogspot.com)