I've seen a lot of threads about mixing cabs, with the general view being that while it can work, it usually introduces another set of potential acoustic problems. However, I was wondering what the bass intelligentsia do when they have cabs that can't be matched: i.e. out of production cabs without a mate, or combos without an extension matched to their internal speaker(s). From what I have gleaned, it seems that the best options (other than just getting different gear) are to match load and impedance and listen for what works and what doesn't. Any other advice?